code: def _get_test_datasets_2d_nonlinear_enhancement():
      data_arrays = _get_test_datasets_2d()
      enh_history = [
          {"gamma": 2.0},
      ]
      for data_arr in data_arrays:
          data_arr.attrs["enhancement_history"] = enh_history
      return data_arrays
  
imports: from datetime import datetime
  from unittest import mock
  import dask.array
  import numpy
  import pytest
  import xarray
label_desc: Use image node_id 2 for calling a global function with example usage: _get_test_datasets_2d_nonlinear_enhancement() and returns: data_arrays