docs: def _get_hydrated_path(field):
      """Return HydratedPath object for file-type field."""
      # Get only file path if whole file object is given.
      if isinstance(field, str) and hasattr(field, 'file_name'):
          # field is already actually a HydratedPath object
          return field
  
      if isinstance(field, dict) and 'file' in field:
          hydrated_path = field['file']
  
      if not hasattr(hydrated_path, 'file_name'):
          raise TypeError("Filter argument must be a valid file-type field.")
  
      return hydrated_path