code: def unit(x):
      """unit return function"""
      return x
  
file_path: popmon/tests/popmon/analysis/test_hist_numpy.py
imports: import histogrammar
  import numpy
  import pandas
  import pytest
  from popmon.analysis.hist_numpy import assert_similar_hists, check_similar_hists, get_2dgrid, get_consistent_numpy_1dhists, get_consistent_numpy_2dgrids, get_consistent_numpy_entries, get_contentType, prepare_2dgrid, set_2dgrid
label_desc: Use image node_id 2 for calling a global function with example usage: unit(x) and returns: x