<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def disconnect(self, name=None):
 """Clear internal Channel cache, allowing currently unused channels to be implictly closed. :param str name: None, to clear the entire cache, or a name string to clear only a certain entry. """

        if name is None:
            self._channels = {}
        else:
            self._channels.pop(name)
        if self._ctxt is not None:
            self._ctxt.disconnect(name)