code: def test_supports_loading_multiple_keys_in_one_call():
      def call_fn(keys):
          return Promise.resolve(keys)
  
      identity_loader = DataLoader(call_fn)
  
      promise_all = identity_loader.load_many([1, 2])
      assert isinstance(promise_all, Promise)
  
      values = promise_all.get()
      assert values == [1, 2]
  
      promise_all = identity_loader.load_many([])
      assert isinstance(promise_all, Promise)
  
      values = promise_all.get()
      assert values == []
  
imports: from pytest import raises
  from promise import Promise, async_instance
  from promise.dataloader import DataLoader
label_desc: Use image node_id 3 for calling a global function with example usage: test_supports_loading_multiple_keys_in_one_call() and returns: Promise