'Loads a :class:`SecureCookie` from a cookie in request.  If the
cookie is not set, a new :class:`SecureCookie` instanced is
returned.
:param request: a request object that has a `cookies` attribute
which is a dict of all cookie values.
:param key: the name of the cookie.
:param secret_key: the secret key used to unquote the cookie.
Always provide the value even though it has
no default!'

@classmethod
def load_cookie(cls, request, key='session', secret_key=None):

    data = request.cookies.get(key)
    if (not data):
        return cls(secret_key=secret_key)
    return cls.unserialize(data, secret_key)
