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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 decode(string):
 """Decode a raw base64 string, returning a bytes object. This function does not parse a full MIME header value encoded with base64 (like =?iso-8895-1?b?bmloISBuaWgh?=) -- please use the high level email.header class for that functionality. """

    if not string:
        return bytes()
    elif isinstance(string, str):
        return a2b_base64(string.encode('raw-unicode-escape'))
    else:
        return a2b_base64(string)