code: def test_rolling_kurt_eq_value_fperr(step):
      # #18804 all rolling kurt for all equal values should return Nan
      # #46717 update: all equal values should return -3 instead of NaN
      a = Series([1.1] * 15).rolling(window=10, step=step).kurt()
      assert (a[a.index >= 9] == -3).all()
      assert a[a.index < 9].isna().all()
  
file_path: pandas/pandas/tests/window/test_rolling_skew_kurt.py
imports: from functools import partial
  import numpy
  import pytest
  from pandas import DataFrame, Series, concat, isna, notna
  import pandas._testing
  from pandas.tseries import offsets
label_desc: Use image node_id 13 for calling a global function with example usage: test_rolling_kurt_eq_value_fperr(step) without return types