code: def test_single_column(df):
      """Test `complete` output if a single column is provided."""
      result = df.complete("names")
      assert_frame_equal(result, df)
  
imports: from string import ascii_lowercase
  import numpy
  import pandas
  import pytest
  from hypothesis import given, settings
  from pandas.testing import assert_frame_equal
  from janitor.testing_utils.strategies import categoricaldf_strategy
label_desc: Use image node_id 26 for calling a global function with example usage: test_single_column(df) without return types