generate a gravatar image url from an e-mail address

gravatar_util.py

import hashlib

def generate_avatar_url(addr, size):
    default = 'mm'# or '404' or 'blank'
    gravatar_base_url = 'http://www.gravatar.com/avatar/'
    computed_hash = hashlib.md5(str(addr).lower().lstrip().rstrip()).hexdigest()                                                                                                  
    return '%s%s?d=%s&s=%s' % (gravatar_base_url, computed_hash, default, size)