code: def df_expand():
      """pytest fixture"""
      # adapted from
      # https://github.com/tidyverse/tidyr/issues/770#issuecomment-993872495
      return pd.DataFrame(
          dict(
              id=pd.Categorical(
                  values=(2, 1, 1, 2, 1),
                  categories=(1, 2, 3),
                  ordered=True,
              ),
              year=(2018, 2018, 2019, 2020, 2020),
              gender=pd.Categorical(
                  ("female", "male", "male", "female", "male")
              ),
              percentage=range(30, 80, 10),
          ),
          index=np.repeat([0], 5),
      )
  
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
label_desc: Use image node_id 30 for calling a global function with example usage: df_expand() and returns: pd