def _find_impl(cls, role, interface):
        """
        Find relation implementation based on its role and interface.
        """
        module = _relation_module(role, interface)
        if not module:
            return None
        return cls._find_subclass(module)
def _find_impl ( cls , role , interface ) : module = _relation_module ( role , interface ) if not module : return None return cls . _find_subclass ( module )
Find relation implementation based on its role and interface.