code: def get_sub(x, idx, window):
      if isinstance(x, (pd.Series, pd.DataFrame)):
          out = x.iloc[idx - window : idx]
          return np.asarray(out)
      return x[idx - window : idx]
  
imports: from io import BytesIO
  from itertools import product
  import warnings
  import numpy
  import pandas
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal
  from statsmodels import tools
  from statsmodels.regression.linear_model import WLS
  from statsmodels.regression.rolling import RollingWLS, RollingOLS
label_desc: Use image node_id 6 for calling a global function with example usage: get_sub(x, idx, window) and returns: x, np