code: def test_coalesce_without_target(df):
      """Test output if `target_column_name` is not provided."""
      result = df.coalesce("a", "b", "c")
      expected_output = df.assign(
          a=df["a"].combine_first(df["b"].combine_first(df["c"]))
      )
      assert_frame_equal(result, expected_output)
  
file_path: pyjanitor/tests/functions/test_coalesce.py
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
label_desc: Use image node_id 7 for calling a global function with example usage: test_coalesce_without_target(df) without return types