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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 Sign(self, message, use_pss=False):
 """Sign a given message."""

    precondition.AssertType(message, bytes)

    # TODO(amoser): This should use PSS by default at some point.
    if not use_pss:
      padding_algorithm = padding.PKCS1v15()
    else:
      padding_algorithm = padding.PSS(
          mgf=padding.MGF1(hashes.SHA256()), salt_length=padding.PSS.MAX_LENGTH)

    return self._value.sign(message, padding_algorithm, hashes.SHA256())