message: Fix multiline magic
diff: @@ -157,7 +157,7 @@ def _update_notebook(original_notebook, original_raw_lines, updated_code_lines):
  code_cell_idx = 0
  for cell in new_notebook["cells"]:
  - if cell["cell_type"] != "code":
  + if not is_python(cell):
  continue
  applicable_lines = [
  