'Check if the user can be assigned an issue on this repository.
:param username: name of the user to check
:type username: str or :class:`User <github3.users.User>`
:returns: :class:`bool`'

def is_assignee(self, username):

    if (not username):
        return False
    url = self._build_url(u'assignees', str(username), base_url=self._api)
    return self._boolean(self._get(url), 204, 404)
