def referenced_ports(self):
        """Return all Ports referenced by this Compound.

        Returns
        -------
        list of mb.Compound
            A list of all ports referenced by the Compound

        """
        from mbuild.port import Port
        return [port for port in self.labels.values()
                if isinstance(port, Port)]
Return all Ports referenced by this Compound.

        Returns
        -------
        list of mb.Compound
            A list of all ports referenced by the Compound