code: def test_find_duplicate():
      l1 = [1, 2, 3, 4, 5, 6]
      assert_(np.rec.find_duplicate(l1) == [])
  
      l2 = [1, 2, 1, 4, 5, 6]
      assert_(np.rec.find_duplicate(l2) == [1])
  
      l3 = [1, 2, 1, 4, 1, 6, 2, 3]
      assert_(np.rec.find_duplicate(l3) == [1, 2])
  
      l3 = [2, 2, 1, 4, 1, 6, 2, 3]
      assert_(np.rec.find_duplicate(l3) == [2, 1])
  
imports: import collections.abc
  import textwrap
  from io import BytesIO
  from os import path
  from pathlib import Path
  import pytest
  import numpy
  from numpy.testing import assert_, assert_equal, assert_array_equal, assert_array_almost_equal, assert_raises, temppath
  from numpy.compat import pickle
label_desc: Use image node_id 1 for calling a global function with example usage: test_find_duplicate() without return types