Unregister a module.

        :param module: must be a string or a module object to unregistered
        :type module: str

def unregister_module(self, module):
        """
        Unregister a module.

        :param module: must be a string or a module object to unregistered
        :type module: str
        """
        if module not in self._namespaces.values():
            raise NoRegisteredError("Module '{0}' is not registered on loader.".format(module))

        for ns, mod in list(self._namespaces.items()):
            if mod == module:
                self.unregister_namespace(ns)