'Request listing, return result.
Result without a message number argument is in form
[\'response\', [\'mesg_num octets\', ...], octets].
Result when a message number argument is given is a
single response: the "scan listing" for that message.'

def list(self, which=None):

    if (which is not None):
        return self._shortcmd(('LIST    %s' % which))
    return self._longcmd('LIST')
