'Tags the job with one or more unique indentifiers.
Tags must be hashable. Duplicate tags are discarded.
:param tags: A unique list of ``Hashable`` tags.
:return: The invoked job instance'

def tag(self, *tags):

    if any([(not isinstance(tag, collections.Hashable)) for tag in tags]):
        raise TypeError('Every    tag    should    be    hashable')
    if (not all((isinstance(tag, collections.Hashable) for tag in tags))):
        raise TypeError('Tags    must    be    hashable')
    self.tags.update(tags)
    return self
