code: def string_var():
      string_var = [
          string.ascii_lowercase[0:5],
          string.ascii_lowercase[5:10],
          string.ascii_lowercase[10:15],
          string.ascii_lowercase[15:20],
          string.ascii_lowercase[20:25],
      ]
      string_var *= 5
      string_var = np.asarray(sorted(string_var))
      series = pd.Series(string_var, name="string_var")
      return series
  
imports: from statsmodels.compat.pandas import assert_frame_equal, assert_series_equal
  from statsmodels.compat.python import lrange
  import string
  import numpy
  from numpy.random import standard_normal
  from numpy.testing import assert_almost_equal, assert_array_equal, assert_equal, assert_string_equal
  import pandas
  import pytest
  from statsmodels.datasets import longley
  from statsmodels.tools import tools
  from statsmodels.tools.tools import pinv_extended
label_desc: Use image node_id 1 for calling a global function with example usage: string_var() and returns: series