code: def df():
      a = np.random.RandomState(0).standard_normal(100)
      b = pd.Series(np.arange(100) % 10, dtype="category")
      return pd.DataFrame({"a": a, "b": b})
  
file_path: statsmodels/statsmodels/stats/tests/test_descriptivestats.py
imports: import numpy
  from numpy.testing import assert_almost_equal, assert_equal
  import pandas
  import scipy.stats
  import pytest
  from statsmodels.iolib.table import SimpleTable
  from statsmodels.stats.descriptivestats import Description, describe, sign_test
label_desc: Use image node_id 1 for calling a global function with example usage: df() and returns: pd