code: def begin_stream(self, command: Command) -> Reply:
          '''Start sending content on the data stream.
  
          Args:
              command: A command that tells the server to send data over the
              data connection.
  
          Coroutine.
  
          Returns:
              The begin reply.
          '''
          yield from self._control_stream.write_command(command)
          reply = yield from self._control_stream.read_reply()
  
          self.raise_if_not_match(
              'Begin stream',
              (
                  ReplyCodes.file_status_okay_about_to_open_data_connection,
                  ReplyCodes.data_connection_already_open_transfer_starting,
              ),
              reply
          )
  
          return replf begin_stream(self, command: Command) -> Reply:
          '''Start sending content on the data stream.
  
          Args:
              command: A command that tells the server to send data over the
              data connection.
  
          Coroutine.
  
          Returns:
              The begin reply.
          '''
          yield from self._control_stream.write_command(command)
          reply = yield from self._control_stream.read_reply()
  
          self.raise_if_not_match(
              'Begin stream',
              (
                  ReplyCodes.file_status_okay_about_to_open_data_connection,
                  ReplyCodes.data_connection_already_open_transfer_starting,
              ),
              reply
          )
  
          return reply
docs: Start sending content on the data stream.
  
          Args:
              command: A command that tells the server to send data over the
              data connection.
  
          Coroutine.
  
          Returns:
              The begin reply.