text: class InvalidChangeMetadata(ValueError):
      """
      A change fragment contains invalid metadata.
      """
  
  
  class FragmentCompilationError(RuntimeError):
      """
      Compiling a change fragment failed.
      """
      def __init__(self, path):
          self.path = path
          RuntimeError.__init__(
              self, 'Failed to process a fragment {}'.format(path))
  