code: def Handle(self, args, token=None):
      
  
      if data_store.RelationalDBEnabled():
        flow_iterator = iteritems(registry.FlowRegistry.FLOW_REGISTRY)
      else:
        flow_iterator = iteritems(registry.AFF4FlowRegistry.FLOW_REGISTRY)
  
      result = []
      for name, cls in sorted(flow_iterator):
  
        # Flows without a category do not show up in the GUI.
        if not getattr(cls, "category", None):
          continue
  
        # Only show flows that the user is allowed to start.
        try:
          if self.access_check_fn:
            self.access_check_fn(token.username, name)
        except access_control.UnauthorizedAccess:
          continue
  
        result.append(ApiFlowDescriptor().InitFromFlowClass(cls, token=token))
  
      return ApiListFlowDescriptorsResult(items=result)
docs: Renders list of descriptors for all the flows.