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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_signed_user(encoded_sig, encoded_data):
 """ Decodes the ``POST``ed signed data """

    decoded_sig = _decode(encoded_sig)
    decoded_data = loads(_decode(encoded_data))

    if decoded_sig != hmac.new(app.config['CANVAS_CLIENT_SECRET'], 
        encoded_data, sha256).digest():
        raise ValueError("sig doesn't match hash")

    return decoded_sig, decoded_data