docs: def _close(self, id):
          """
          Respond to a CLOSE command, dumping some data onto the stream.  As with
          WRITE, this returns an empty acknowledgement.
  
          An occurrence of I{Close} on the wire, together with the response
          generated by this method, might have this apperance::
  
              C: -Command: Close
              C: -Ask: 1
              C: Id: glyph@divmod.com->radix@twistedmatrix.com:q2q-example:0
              C:
              S: -Answer: 1
              S:
  
          """
          # The connection is removed from the mapping by connectionLost.
          connection = self.connections[id]
          connection.connectionLost(Failure(CONNECTION_DONE))
          return {}