Return the first child found with tag in *tagnames*, or None if
        not found.

def first_child_found_in(self, *tagnames):
        """
        Return the first child found with tag in *tagnames*, or None if
        not found.
        """
        for tagname in tagnames:
            child = self.find(qn(tagname))
            if child is not None:
                return child
        return None