docs: def validate_mapping(mapping):
      """ Validate a mapping configuration file against the relevant schema. """
      file_path = os.path.join(os.path.dirname(__file__),
                               'schemas', 'mapping.json')
      with open(file_path, 'r') as fh:
          validator = Draft4Validator(json.load(fh))
          validator.validate(mapping)
      return mapping