code: def test_batch_time_frame():
      tf0 = zb.time_frame(
          {"x": [1, 2, 3]},
          start="2020",
          freq="D",
          metadata={"item_id": 0},
      )
      tf1 = zb.time_frame({"x": [4, 5, 6]})
  
      batched = zb.batch([tf0, tf1])
  
      assert len(batched) == 3
      assert batched.batch_size == 2
  
      tf0x, tf1x = batched.items()
  
imports: import pytest
  import numpy
  import gluonts.zebras
label_desc: Use image node_id 2 for calling a global function with example usage: test_batch_time_frame() without return types