def METHOD_NAME(self, *others):
    """
    Lowest common ancestor, i.e., longest common prefix of paths
    ::
        assert Ltree('1.2.3.4.5').lca('1.2.3', '1.2.3.4', '1.2.3') == '1.2'
    """
    other_parts = [Ltree(other).path.split('.') for other in others]
    parts = self.path.split('.')
    for index, element in enumerate(parts):
        if any(
            other[index] != element or
            len(other) <= index + 1 or
            len(parts) == index + 1
            for other in other_parts
        ):
            if index == 0:
                return None
            return Ltree('.'.join(parts[0:index]))