Read the documents in this collection.

        This sends a ``RunQuery`` RPC and then returns an iterator which
        consumes each document returned in the stream of ``RunQueryResponse``
        messages.

        .. note::

           The underlying stream of responses will time out after
           the ``max_rpc_timeout_millis`` value set in the GAPIC
           client configuration for the ``RunQuery`` API.  Snapshots
           not consumed from the iterator before that point will be lost.

        If a ``transaction`` is used and it already has write operations
        added, this method cannot be used (i.e. read-after-write is not
        allowed).

        Args:
            transaction (Optional[~.firestore_v1beta1.transaction.\
                Transaction]): An existing transaction that the query will
                run in.

        Yields:
            ~.firestore_v1beta1.document.DocumentSnapshot: The next
            document that fulfills the query.

def stream(self, transaction=None):
        """Read the documents in this collection.

        This sends a ``RunQuery`` RPC and then returns an iterator which
        consumes each document returned in the stream of ``RunQueryResponse``
        messages.

        .. note::

           The underlying stream of responses will time out after
           the ``max_rpc_timeout_millis`` value set in the GAPIC
           client configuration for the ``RunQuery`` API.  Snapshots
           not consumed from the iterator before that point will be lost.

        If a ``transaction`` is used and it already has write operations
        added, this method cannot be used (i.e. read-after-write is not
        allowed).

        Args:
            transaction (Optional[~.firestore_v1beta1.transaction.\
                Transaction]): An existing transaction that the query will
                run in.

        Yields:
            ~.firestore_v1beta1.document.DocumentSnapshot: The next
            document that fulfills the query.
        """
        query = query_mod.Query(self)
        return query.stream(transaction=transaction)