docs: 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)