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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 base64url_decode(input):
 """Helper method to base64url_decode a string. Args: input (str):
 A base64url_encoded string to decode. """

    rem = len(input) % 4

    if rem > 0:
        input += b'=' * (4 - rem)

    return base64.urlsafe_b64decode(input)