#golang style errors in python. like it so far.

golang_errors.py

@app.route("/<user_id>/facebook_id", methods=["PUT"])
def put_facebook_id(user_id):
    fb_d, err = get_facebook_data_from_cookie(request)
    if err:
        return json_error(err)
    else:
        # save and return success
        pass

def get_facebook_data_from_cookie(request):
    c_name = "fbsr_%s" % settings.FACEBOOK_APP_ID
    c = request.cookies.get(c_name)
    if not c:
        return {}, "no facebook cookie in request"

    d, err = validate_signed_request(c)
    if err:
        return {}, "invalid facebook signed_request"
    else:
        return d, None
        
def json_error(msg):
    return json.dumps({'error': msg}), 400