Return the vCard corresponding to the uid
        filename  -- unused, for API compatibility only
        uid -- the UID to get (required)

def to_vobject(self, filename=None, uid=None):
        """Return the vCard corresponding to the uid
        filename  -- unused, for API compatibility only
        uid -- the UID to get (required)
        """
        self._update()
        return self._to_vcard(self._book[uid.split('@')[0]])