Handle OAuthRateLimitException response

Need to handle the following response which is a different format to the documented api responses.

content = 
{
    "code": 420,
    "error_type": "OAuthRateLimitException",
    "error_message": "You have exceeded the maximum number of requests per hour. You have performed a total of 5001 requests in the last hour. Our general maximum request limit is set at 5000 requests per hour."
}

response = 
{
    'status': '400',
    'content-length': '264',
    'content-language': 'en',
    'vary': 'Accept-Language,
    Cookie',
    'server': 'nginx',
    'connection': 'keep-alive',
    'date': 'Tue,
    31Jul201202: 53: 33GMT',
    'content-type': 'application/json'
}