def depth(self) -> int:
        """ Depth of the citation scheme

        .. example:: If we have a Book, Poem, Line system, and the citation we are looking at is Poem, depth is 1


        :rtype: int
        :return: Depth of the citation scheme
        """
        if len(self.children):
            return 1 + max([child.depth for child in self.children])
        else:
            return 1
Depth of the citation scheme

        .. example:: If we have a Book, Poem, Line system, and the citation we are looking at is Poem, depth is 1


        :rtype: int
        :return: Depth of the citation scheme