Return dictionary of non-YANG capabilities.

        Only capabilities from the `CAPABILITIES` dictionary are taken
        into account.

def registered_capabilities(self):
        """Return dictionary of non-YANG capabilities.

        Only capabilities from the `CAPABILITIES` dictionary are taken
        into account.
        """
        return dict ([ (CAPABILITIES[c.id],c) for c in self.capabilities
                 if c.id in CAPABILITIES ])