code: def test_existing_property(feature_seq, runner):
      result = runner.invoke(
          main_group,
          ["calc", "AREA", "f.properties.AREA * 2"],
          feature_seq,
      )
      assert result.exit_code == 2
  
      result = runner.invoke(
          main_group,
          ["calc", "--overwrite", "AREA", "f.properties.AREA * 2"],
          feature_seq,
      )
      assert result.exit_code == 0
      feats = _load(result.output)
      assert len(feats) == 2
      for feat in feats:
          assert "AREA" in feat["properties"]
  
file_path: Fiona/tests/test_fio_calc.py
imports: import json
  from click.testing import CliRunner
  from fiona.fio.main import main_group
label_desc: Use image node_id 5 for calling a global function with example usage: test_existing_property(feature_seq, runner) without return types