code: def _get_action(self, action):
          
  
          # If we don't have an action named that, bail out
          if action not in self.wsgi_actions:
              return None
  
          # Generate an ActionDescriptor if necessary
          if action not in self.wsgi_descriptors:
              self.wsgi_descriptors[action] = actions.ActionDescriptor(
                  self.wsgi_actions[action],
                  self.wsgi_extensions.get(action, []),
                  self.wsgi_resp_type)
  
          # OK, return the method descriptor
          return self.wsgi_descriptors[action]
docs: Retrieve a descriptor for the named action.  Caches
          descriptors for efficiency.