Tokens, along with their syntactic information, in the input
document. Populated if the user enables [AnnotateTextRequest.F
eatures.extract_syntax][google.cloud.language.v1beta2.Annotat
eTextRequest.Features.extract_syntax].
The overall sentiment for the document. Populated if the user
enables [AnnotateTextRequest.Features.extract_document_senti
ment][google.cloud.language.v1beta2.AnnotateTextRequest.Featur
es.extract_document_sentiment].