code: def test_partition_first_items(xs):
      """retrieving the first item of each grouping recovers the original list."""
      rt = list(map(lambda pair: pair[0], u.partition(xs, 1)))
      assert rt == xs
  
imports: import itertools
  import json
  import os
  import uuid
  from collections import OrderedDict
  from enum import Enum
  from typing import Union
  import hypothesis.strategies
  from hypothesis import given
  import caliban.util
  import pytest
label_desc: Use image node_id 17 for calling a global function with example usage: test_partition_first_items(xs) without return types