'Parse the signature *sig* into individual nodes and append them to
*signode*. If ValueError is raised, parsing is aborted and the whole
*sig* is put into a single desc_name node.
The return value should be a value that identifies the object.  It is
passed to :meth:`add_target_and_index()` unchanged, and otherwise only
used to skip duplicates.'

def handle_signature(self, sig, signode):

    raise ValueError
