code: def test_area_conversion(dataframe):
      df = dataframe.convert_units(
          "a",
          existing_units="cm**2",
          to_units="m**2",
          dest_column_name="a_m2",
      )
      assert df["a"].sum() == pytest.approx(
          df["a_m2"].sum() * (100.0**2)
      )
  
file_path: pyjanitor/tests/engineering/test_convert_units.py
imports: import pytest
  from unyt.exceptions import UnitConversionError
  from janitor.engineering import convert_units
label_desc: Use image node_id 7 for calling a global function with example usage: test_area_conversion(dataframe) without return types