code: def test_expand_and_concat():
      data = {
          "col1": ["A, B", "B, C, D", "E, F", "A, E, F"],
          "col2": [1, 2, 3, 4],
      }
  
      df = pd.DataFrame(data).expand_column(
          column_name="col1", sep=", ", concat=True
      )
      assert df.shape[1] == 8
  
imports: import pandas
  import pytest
label_desc: Use image node_id 2 for calling a global function with example usage: test_expand_and_concat() without return types