'Return a list of start and end index for the first sequence of
characters between INDEX1 and INDEX2 which all have tag TAGNAME.
The text is searched forward from INDEX1.'

def tag_nextrange(self, tagName, index1, index2=None):

    return self.tk.splitlist(self.tk.call(self._w, 'tag', 'nextrange', tagName, index1, index2))
