def METHOD_NAME(self, extensions):
    super(DriverManager, self).METHOD_NAME(extensions)
    if not self.extensions:
        name = self._names[0]
        raise NoMatches('No %r driver found, looking for %r' %
                        (self.namespace, name))
    if len(self.extensions) > 1:
        discovered_drivers = ','.join(e.entry_point_target
                                      for e in self.extensions)
        raise MultipleMatches('Multiple %r drivers found: %s' %
                              (self.namespace, discovered_drivers))