message: Make it easier to disable specific features.
diff: @@ -129,6 +129,18 @@ class Feature(enum.Enum):
  LISTS = 'LISTS'
  NAME_SCOPES = 'NAME_SCOPES'
  + @classmethod
  + def all(cls):
  + """Returns a tuple that enables all options."""
  + return tuple(cls.__members__.values())
  +
  + @classmethod
  + def all_but(cls, exclude):
  + """Returns a tuple that enables all but the excluded options."""
  + if not isinstance(exclude, (list, tuple, set)):
  + exclude = (exclude,)
  + return tuple(set(cls.all()) - set(exclude) - {cls.ALL})
  +
  class ConversionOptions(object):
  """Immutable container for global conversion flags.
  