Connect an output to any callable object.

        :param str output_name: the output to connect. Must be one of
            the ``'self'`` outputs in the ``linkages`` parameter.

        :param callable input_method: the thread-safe callable to invoke
            when :py:meth:`send` is called.

def connect(self, output_name, input_method):
        """Connect an output to any callable object.

        :param str output_name: the output to connect. Must be one of
            the ``'self'`` outputs in the ``linkages`` parameter.

        :param callable input_method: the thread-safe callable to invoke
            when :py:meth:`send` is called.

        """
        src, outbox = self._compound_outputs[output_name]
        self._compound_children[src].connect(outbox, input_method)