'Add and/or remove specified tags to the tests in this suite.
:param add: Tags to add as a list or, if adding only one,
as a single string.
:param remove: Tags to remove as a list or as a single string.
Can be given as patterns where ``*`` and ``?`` work as wildcards.
:param persist: Add/remove specified tags also to new tests added
to this suite in the future.'

def set_tags(self, add=None, remove=None, persist=False):

    setter = TagSetter(add, remove)
    self.visit(setter)
    if persist:
        self._my_visitors.append(setter)
