// Create a reference to the cities collection
const citiesRef = db.collection('cities');
// Create a query against the collection
const queryRef = citiesRef.where('state', '==', 'CA');
# Create a reference to the cities collection
cities_ref = db.collection(u'cities')
# Create a query against the collection
query_ref = cities_ref.where(u'state', u'==', u'CA')