Class ContextsClient (2.23.3)

ContextsClient(*, credentials: typing.Optional[google.auth.credentials.Credentials] = None, transport: typing.Optional[typing.Union[str, google.cloud.dialogflow_v2.services.contexts.transports.base.ContextsTransport]] = None, client_options: typing.Optional[typing.Union[google.api_core.client_options.ClientOptions, dict]] = None, client_info: google.api_core.gapic_v1.client_info.ClientInfo = <google.api_core.gapic_v1.client_info.ClientInfo object>)

Service for managing Contexts.

Properties

transport

Returns the transport used by the client instance.

Returns
TypeDescription
ContextsTransportThe transport used by the client instance.

Methods

ContextsClient

ContextsClient(*, credentials: typing.Optional[google.auth.credentials.Credentials] = None, transport: typing.Optional[typing.Union[str, google.cloud.dialogflow_v2.services.contexts.transports.base.ContextsTransport]] = None, client_options: typing.Optional[typing.Union[google.api_core.client_options.ClientOptions, dict]] = None, client_info: google.api_core.gapic_v1.client_info.ClientInfo = <google.api_core.gapic_v1.client_info.ClientInfo object>)

Instantiates the contexts client.

Parameters
NameDescription
credentials Optional[google.auth.credentials.Credentials]

The authorization credentials to attach to requests. These credentials identify the application to the service; if none are specified, the client will attempt to ascertain the credentials from the environment.

transport Union[str, ContextsTransport]

The transport to use. If set to None, a transport is chosen automatically.

client_options Optional[Union[google.api_core.client_options.ClientOptions, dict]]

Custom options for the client. It won't take effect if a transport instance is provided. (1) The api_endpoint property can be used to override the default endpoint provided by the client. GOOGLE_API_USE_MTLS_ENDPOINT environment variable can also be used to override the endpoint: "always" (always use the default mTLS endpoint), "never" (always use the default regular endpoint) and "auto" (auto switch to the default mTLS endpoint if client certificate is present, this is the default value). However, the api_endpoint property takes precedence if provided. (2) If GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable is "true", then the client_cert_source property can be used to provide client certificate for mutual TLS transport. If not provided, the default SSL client certificate will be used if present. If GOOGLE_API_USE_CLIENT_CERTIFICATE is "false" or not set, no client certificate will be used.

client_info google.api_core.gapic_v1.client_info.ClientInfo

The client info used to send a user-agent string along with API requests. If None, then default info will be used. Generally, you only need to set this if you're developing your own client library.

Exceptions
TypeDescription
google.auth.exceptions.MutualTLSChannelErrorIf mutual TLS transport creation failed for any reason.

__exit__

__exit__(type, value, traceback)

Releases underlying transport's resources.

cancel_operation

cancel_operation(
    request: typing.Optional[
        google.longrunning.operations_pb2.CancelOperationRequest
    ] = None,
    *,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> None

Starts asynchronous cancellation on a long-running operation.

The server makes a best effort to cancel the operation, but success is not guaranteed. If the server doesn't support this method, it returns google.rpc.Code.UNIMPLEMENTED.

Parameters
NameDescription
request .operations_pb2.CancelOperationRequest

The request object. Request message for CancelOperation method.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

common_billing_account_path

common_billing_account_path(billing_account: str) -> str

Returns a fully-qualified billing_account string.

common_folder_path

common_folder_path(folder: str) -> str

Returns a fully-qualified folder string.

common_location_path

common_location_path(project: str, location: str) -> str

Returns a fully-qualified location string.

common_organization_path

common_organization_path(organization: str) -> str

Returns a fully-qualified organization string.

common_project_path

common_project_path(project: str) -> str

Returns a fully-qualified project string.

context_path

context_path(project: str, session: str, context: str) -> str

Returns a fully-qualified context string.

create_context

create_context(
    request: typing.Optional[
        typing.Union[
            google.cloud.dialogflow_v2.types.context.CreateContextRequest, dict
        ]
    ] = None,
    *,
    parent: typing.Optional[str] = None,
    context: typing.Optional[google.cloud.dialogflow_v2.types.context.Context] = None,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.cloud.dialogflow_v2.types.context.Context

Creates a context. If the specified context already exists, overrides the context.

# This snippet has been automatically generated and should be regarded as a
# code template only.
# It will require modifications to work:
# - It may require correct/in-range values for request initialization.
# - It may require specifying regional endpoints when creating the service
#   client as shown in:
#   https://googleapis.dev/python/google-api-core/latest/client_options.html
from google.cloud import dialogflow_v2

def sample_create_context():
    # Create a client
    client = dialogflow_v2.ContextsClient()

    # Initialize request argument(s)
    context = dialogflow_v2.Context()
    context.name = "name_value"

    request = dialogflow_v2.CreateContextRequest(
        parent="parent_value",
        context=context,
    )

    # Make the request
    response = client.create_context(request=request)

    # Handle the response
    print(response)
Parameters
NameDescription
request Union[google.cloud.dialogflow_v2.types.CreateContextRequest, dict]

The request object. The request message for Contexts.CreateContext.

parent str

Required. The session to create a context for. Format: projects/ or projects/. If Environment ID is not specified, we assume default 'draft' environment. If User ID is not specified, we assume default '-' user. This corresponds to the parent field on the request instance; if request is provided, this should not be set.

context google.cloud.dialogflow_v2.types.Context

Required. The context to create. This corresponds to the context field on the request instance; if request is provided, this should not be set.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
google.cloud.dialogflow_v2.types.ContextDialogflow contexts are similar to natural language context. If a person says to you "they are orange", you need context in order to understand what "they" is referring to. Similarly, for Dialogflow to handle an end-user expression like that, it needs to be provided with context in order to correctly match an intent. Using contexts, you can control the flow of a conversation. You can configure contexts for an intent by setting input and output contexts, which are identified by string names. When an intent is matched, any configured output contexts for that intent become active. While any contexts are active, Dialogflow is more likely to match intents that are configured with input contexts that correspond to the currently active contexts. For more information about context, see the [Contexts guide](\ https://cloud.google.com/dialogflow/docs/contexts-overview).

delete_all_contexts

delete_all_contexts(
    request: typing.Optional[
        typing.Union[
            google.cloud.dialogflow_v2.types.context.DeleteAllContextsRequest, dict
        ]
    ] = None,
    *,
    parent: typing.Optional[str] = None,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> None

Deletes all active contexts in the specified session.

# This snippet has been automatically generated and should be regarded as a
# code template only.
# It will require modifications to work:
# - It may require correct/in-range values for request initialization.
# - It may require specifying regional endpoints when creating the service
#   client as shown in:
#   https://googleapis.dev/python/google-api-core/latest/client_options.html
from google.cloud import dialogflow_v2

def sample_delete_all_contexts():
    # Create a client
    client = dialogflow_v2.ContextsClient()

    # Initialize request argument(s)
    request = dialogflow_v2.DeleteAllContextsRequest(
        parent="parent_value",
    )

    # Make the request
    client.delete_all_contexts(request=request)
Parameters
NameDescription
request Union[google.cloud.dialogflow_v2.types.DeleteAllContextsRequest, dict]

The request object. The request message for Contexts.DeleteAllContexts.

parent str

Required. The name of the session to delete all contexts from. Format: projects/ or projects/. If Environment ID is not specified we assume default 'draft' environment. If User ID is not specified, we assume default '-' user. This corresponds to the parent field on the request instance; if request is provided, this should not be set.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

delete_context

delete_context(
    request: typing.Optional[
        typing.Union[
            google.cloud.dialogflow_v2.types.context.DeleteContextRequest, dict
        ]
    ] = None,
    *,
    name: typing.Optional[str] = None,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> None

Deletes the specified context.

# This snippet has been automatically generated and should be regarded as a
# code template only.
# It will require modifications to work:
# - It may require correct/in-range values for request initialization.
# - It may require specifying regional endpoints when creating the service
#   client as shown in:
#   https://googleapis.dev/python/google-api-core/latest/client_options.html
from google.cloud import dialogflow_v2

def sample_delete_context():
    # Create a client
    client = dialogflow_v2.ContextsClient()

    # Initialize request argument(s)
    request = dialogflow_v2.DeleteContextRequest(
        name="name_value",
    )

    # Make the request
    client.delete_context(request=request)
Parameters
NameDescription
request Union[google.cloud.dialogflow_v2.types.DeleteContextRequest, dict]

The request object. The request message for Contexts.DeleteContext.

name str

Required. The name of the context to delete. Format: projects/ or projects/. If Environment ID is not specified, we assume default 'draft' environment. If User ID is not specified, we assume default '-' user. This corresponds to the name field on the request instance; if request is provided, this should not be set.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

from_service_account_file

from_service_account_file(filename: str, *args, **kwargs)

Creates an instance of this client using the provided credentials file.

Parameter
NameDescription
filename str

The path to the service account private key json file.

Returns
TypeDescription
ContextsClientThe constructed client.

from_service_account_info

from_service_account_info(info: dict, *args, **kwargs)

Creates an instance of this client using the provided credentials info.

Parameter
NameDescription
info dict

The service account private key info.

Returns
TypeDescription
ContextsClientThe constructed client.

from_service_account_json

from_service_account_json(filename: str, *args, **kwargs)

Creates an instance of this client using the provided credentials file.

Parameter
NameDescription
filename str

The path to the service account private key json file.

Returns
TypeDescription
ContextsClientThe constructed client.

get_context

get_context(
    request: typing.Optional[
        typing.Union[google.cloud.dialogflow_v2.types.context.GetContextRequest, dict]
    ] = None,
    *,
    name: typing.Optional[str] = None,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.cloud.dialogflow_v2.types.context.Context

Retrieves the specified context.

# This snippet has been automatically generated and should be regarded as a
# code template only.
# It will require modifications to work:
# - It may require correct/in-range values for request initialization.
# - It may require specifying regional endpoints when creating the service
#   client as shown in:
#   https://googleapis.dev/python/google-api-core/latest/client_options.html
from google.cloud import dialogflow_v2

def sample_get_context():
    # Create a client
    client = dialogflow_v2.ContextsClient()

    # Initialize request argument(s)
    request = dialogflow_v2.GetContextRequest(
        name="name_value",
    )

    # Make the request
    response = client.get_context(request=request)

    # Handle the response
    print(response)
Parameters
NameDescription
request Union[google.cloud.dialogflow_v2.types.GetContextRequest, dict]

The request object. The request message for Contexts.GetContext.

name str

Required. The name of the context. Format: projects/ or projects/. If Environment ID is not specified, we assume default 'draft' environment. If User ID is not specified, we assume default '-' user. This corresponds to the name field on the request instance; if request is provided, this should not be set.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
google.cloud.dialogflow_v2.types.ContextDialogflow contexts are similar to natural language context. If a person says to you "they are orange", you need context in order to understand what "they" is referring to. Similarly, for Dialogflow to handle an end-user expression like that, it needs to be provided with context in order to correctly match an intent. Using contexts, you can control the flow of a conversation. You can configure contexts for an intent by setting input and output contexts, which are identified by string names. When an intent is matched, any configured output contexts for that intent become active. While any contexts are active, Dialogflow is more likely to match intents that are configured with input contexts that correspond to the currently active contexts. For more information about context, see the [Contexts guide](\ https://cloud.google.com/dialogflow/docs/contexts-overview).

get_location

get_location(
    request: typing.Optional[
        google.cloud.location.locations_pb2.GetLocationRequest
    ] = None,
    *,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.cloud.location.locations_pb2.Location

Gets information about a location.

Parameters
NameDescription
request .location_pb2.GetLocationRequest

The request object. Request message for GetLocation method.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
.location_pb2.LocationLocation object.

get_mtls_endpoint_and_cert_source

get_mtls_endpoint_and_cert_source(
    client_options: typing.Optional[
        google.api_core.client_options.ClientOptions
    ] = None,
)

Return the API endpoint and client cert source for mutual TLS.

The client cert source is determined in the following order: (1) if GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable is not "true", the client cert source is None. (2) if client_options.client_cert_source is provided, use the provided one; if the default client cert source exists, use the default one; otherwise the client cert source is None.

The API endpoint is determined in the following order: (1) if client_options.api_endpoint if provided, use the provided one. (2) if GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable is "always", use the default mTLS endpoint; if the environment variable is "never", use the default API endpoint; otherwise if client cert source exists, use the default mTLS endpoint, otherwise use the default API endpoint.

More details can be found at https://google.aip.dev/auth/4114.

Parameter
NameDescription
client_options google.api_core.client_options.ClientOptions

Custom options for the client. Only the api_endpoint and client_cert_source properties may be used in this method.

Exceptions
TypeDescription
google.auth.exceptions.MutualTLSChannelErrorIf any errors happen.
Returns
TypeDescription
Tuple[str, Callable[[], Tuple[bytes, bytes]]]returns the API endpoint and the client cert source to use.

get_operation

get_operation(
    request: typing.Optional[
        google.longrunning.operations_pb2.GetOperationRequest
    ] = None,
    *,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.longrunning.operations_pb2.Operation

Gets the latest state of a long-running operation.

Parameters
NameDescription
request .operations_pb2.GetOperationRequest

The request object. Request message for GetOperation method.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
.operations_pb2.OperationAn Operation object.

list_contexts

list_contexts(
    request: typing.Optional[
        typing.Union[google.cloud.dialogflow_v2.types.context.ListContextsRequest, dict]
    ] = None,
    *,
    parent: typing.Optional[str] = None,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.cloud.dialogflow_v2.services.contexts.pagers.ListContextsPager

Returns the list of all contexts in the specified session.

# This snippet has been automatically generated and should be regarded as a
# code template only.
# It will require modifications to work:
# - It may require correct/in-range values for request initialization.
# - It may require specifying regional endpoints when creating the service
#   client as shown in:
#   https://googleapis.dev/python/google-api-core/latest/client_options.html
from google.cloud import dialogflow_v2

def sample_list_contexts():
    # Create a client
    client = dialogflow_v2.ContextsClient()

    # Initialize request argument(s)
    request = dialogflow_v2.ListContextsRequest(
        parent="parent_value",
    )

    # Make the request
    page_result = client.list_contexts(request=request)

    # Handle the response
    for response in page_result:
        print(response)
Parameters
NameDescription
request Union[google.cloud.dialogflow_v2.types.ListContextsRequest, dict]

The request object. The request message for Contexts.ListContexts.

parent str

Required. The session to list all contexts from. Format: projects/ or projects/. If Environment ID is not specified, we assume default 'draft' environment. If User ID is not specified, we assume default '-' user. This corresponds to the parent field on the request instance; if request is provided, this should not be set.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
google.cloud.dialogflow_v2.services.contexts.pagers.ListContextsPagerThe response message for Contexts.ListContexts. Iterating over this object will yield results and resolve additional pages automatically.

list_locations

list_locations(
    request: typing.Optional[
        google.cloud.location.locations_pb2.ListLocationsRequest
    ] = None,
    *,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.cloud.location.locations_pb2.ListLocationsResponse

Lists information about the supported locations for this service.

Parameters
NameDescription
request .location_pb2.ListLocationsRequest

The request object. Request message for ListLocations method.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
.location_pb2.ListLocationsResponseResponse message for ListLocations method.

list_operations

list_operations(
    request: typing.Optional[
        google.longrunning.operations_pb2.ListOperationsRequest
    ] = None,
    *,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.longrunning.operations_pb2.ListOperationsResponse

Lists operations that match the specified filter in the request.

Parameters
NameDescription
request .operations_pb2.ListOperationsRequest

The request object. Request message for ListOperations method.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
.operations_pb2.ListOperationsResponseResponse message for ListOperations method.

parse_common_billing_account_path

parse_common_billing_account_path(path: str) -> typing.Dict[str, str]

Parse a billing_account path into its component segments.

parse_common_folder_path

parse_common_folder_path(path: str) -> typing.Dict[str, str]

Parse a folder path into its component segments.

parse_common_location_path

parse_common_location_path(path: str) -> typing.Dict[str, str]

Parse a location path into its component segments.

parse_common_organization_path

parse_common_organization_path(path: str) -> typing.Dict[str, str]

Parse a organization path into its component segments.

parse_common_project_path

parse_common_project_path(path: str) -> typing.Dict[str, str]

Parse a project path into its component segments.

parse_context_path

parse_context_path(path: str) -> typing.Dict[str, str]

Parses a context path into its component segments.

update_context

update_context(
    request: typing.Optional[
        typing.Union[
            google.cloud.dialogflow_v2.types.context.UpdateContextRequest, dict
        ]
    ] = None,
    *,
    context: typing.Optional[google.cloud.dialogflow_v2.types.context.Context] = None,
    update_mask: typing.Optional[google.protobuf.field_mask_pb2.FieldMask] = None,
    retry: typing.Union[
        google.api_core.retry.Retry, google.api_core.gapic_v1.method._MethodDefault
    ] = _MethodDefault._DEFAULT_VALUE,
    timeout: typing.Union[float, object] = _MethodDefault._DEFAULT_VALUE,
    metadata: typing.Sequence[typing.Tuple[str, str]] = ()
) -> google.cloud.dialogflow_v2.types.context.Context

Updates the specified context.

# This snippet has been automatically generated and should be regarded as a
# code template only.
# It will require modifications to work:
# - It may require correct/in-range values for request initialization.
# - It may require specifying regional endpoints when creating the service
#   client as shown in:
#   https://googleapis.dev/python/google-api-core/latest/client_options.html
from google.cloud import dialogflow_v2

def sample_update_context():
    # Create a client
    client = dialogflow_v2.ContextsClient()

    # Initialize request argument(s)
    context = dialogflow_v2.Context()
    context.name = "name_value"

    request = dialogflow_v2.UpdateContextRequest(
        context=context,
    )

    # Make the request
    response = client.update_context(request=request)

    # Handle the response
    print(response)
Parameters
NameDescription
request Union[google.cloud.dialogflow_v2.types.UpdateContextRequest, dict]

The request object. The request message for Contexts.UpdateContext.

context google.cloud.dialogflow_v2.types.Context

Required. The context to update. This corresponds to the context field on the request instance; if request is provided, this should not be set.

update_mask google.protobuf.field_mask_pb2.FieldMask

Optional. The mask to control which fields get updated. This corresponds to the update_mask field on the request instance; if request is provided, this should not be set.

retry google.api_core.retry.Retry

Designation of what errors, if any, should be retried.

timeout float

The timeout for this request.

metadata Sequence[Tuple[str, str]]

Strings which should be sent along with the request as metadata.

Returns
TypeDescription
google.cloud.dialogflow_v2.types.ContextDialogflow contexts are similar to natural language context. If a person says to you "they are orange", you need context in order to understand what "they" is referring to. Similarly, for Dialogflow to handle an end-user expression like that, it needs to be provided with context in order to correctly match an intent. Using contexts, you can control the flow of a conversation. You can configure contexts for an intent by setting input and output contexts, which are identified by string names. When an intent is matched, any configured output contexts for that intent become active. While any contexts are active, Dialogflow is more likely to match intents that are configured with input contexts that correspond to the currently active contexts. For more information about context, see the [Contexts guide](\ https://cloud.google.com/dialogflow/docs/contexts-overview).