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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def gravatar_url(email, size=32):
 """ Return the full URL for a Gravatar given an email hash. """

    bits = (md5(email.lower().encode("utf-8")).hexdigest(), size)
    return "//www.gravatar.com/avatar/%s?s=%s&d=identicon&r=PG" % bits