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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def commit( self, project_id, mode, mutations, transaction=None, retry=google.api_core.gapic_v1.method.DEFAULT, timeout=google.api_core.gapic_v1.method.DEFAULT, metadata=None, ):
 """ Commits a transaction, optionally creating, deleting or modifying some entities. Example: Args: project_id (str):
 The ID of the project against which to make the request. mode (~google.cloud.datastore_v1.types.Mode):
 The type of commit to perform. Defaults to ``TRANSACTIONAL``. mutations (list[Union[dict, ~google.cloud.datastore_v1.types.Mutation]]):
 The mutations to perform. When mode is ``TRANSACTIONAL``, mutations affecting a single entity are applied in order. The following sequences of mutations affecting a single entity are not permitted in a single ``Commit`` request: - ``insert`` followed by ``insert`` - ``update`` followed by ``insert`` - ``upsert`` followed by ``insert`` - ``delete`` followed by ``update`` When mode is ``NON_TRANSACTIONAL``, no two mutations may affect a single entity. If a dict is provided, it must be of the same form as the protobuf message :class:`~google.cloud.datastore_v1.types.Mutation` transaction (bytes):
 The identifier of the transaction associated with the commit. A transaction identifier is returned by a call to ``Datastore.BeginTransaction``. retry (Optional[google.api_core.retry.Retry]):
 A retry object used to retry requests. If ``None`` is specified, requests will not be retried. timeout (Optional[float]):
 The amount of time, in seconds, to wait for the request to complete. Note that if ``retry`` is specified, the timeout applies to each individual attempt. metadata (Optional[Sequence[Tuple[str, str]]]):
 Additional metadata that is provided to the method. Returns: A :class:`~google.cloud.datastore_v1.types.CommitResponse` instance. Raises: google.api_core.exceptions.GoogleAPICallError: If the request failed for any reason. google.api_core.exceptions.RetryError: If the request failed due to a retryable error and retry attempts failed. ValueError: If the parameters are invalid. """

        # Wrap the transport method to add retry and timeout logic.
        if "commit" not in self._inner_api_calls:
            self._inner_api_calls[
                "commit"
            ] = google.api_core.gapic_v1.method.wrap_method(
                self.transport.commit,
                default_retry=self._method_configs["Commit"].retry,
                default_timeout=self._method_configs["Commit"].timeout,
                client_info=self._client_info,
            )

        # Sanity check: We have some fields which are mutually exclusive;
        # raise ValueError if more than one is sent.
        google.api_core.protobuf_helpers.check_oneof(transaction=transaction)

        request = datastore_pb2.CommitRequest(
            project_id=project_id,
            mode=mode,
            mutations=mutations,
            transaction=transaction,
        )
        if metadata is None:
            metadata = []
        metadata = list(metadata)
        try:
            routing_header = [("project_id", project_id)]
        except AttributeError:
            pass
        else:
            routing_metadata = google.api_core.gapic_v1.routing_header.to_grpc_metadata(
                routing_header
            )
            metadata.append(routing_metadata)

        return self._inner_api_calls["commit"](
            request, retry=retry, timeout=timeout, metadata=metadata
        )