docs: def feedback(self, *, out_port=None, in_port=None):
          """Return a circuit with self-feedback from the output port
          (zero-based) ``out_port`` to the input port ``in_port``.
  
          Args:
              out_port (int or None): The output port from which the feedback
                  connection leaves (zero-based, default ``None`` corresponds
                  to the *last* port).
              in_port (int or None): The input port into which the feedback
                  connection goes (zero-based, default ``None`` corresponds to
                  the *last* port).
          """
          if out_port is None:
              out_port = self.cdim - 1
          if in_port is None:
              in_port = self.cdim - 1
          return self._feedback(out_port=out_port, in_port=in_port)