'Create a deploy key.
:param str title: (required), title of key
:param str key: (required), key text
:param bool read_only: (optional), restrict key access to read-only,
default is False
:returns: :class:`~github3.users.Key` if successful, else None'

@requires_auth
def create_key(self, title, key, read_only=False):

    json = None
    if (title and key):
        data = {u'title': title, u'key': key, u'read_only': read_only}
        url = self._build_url(u'keys', base_url=self._api)
        json = self._json(self._post(url, data=data), 201)
    return self._instance_or_null(users.Key, json)
