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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 ensure(assertion, message=None):
 """ Checks an assertion argument for truth-ness. Will return ``True`` or explicitly raise ``AssertionError``. This is to deal with environments using ``python -O` or ``PYTHONOPTIMIZE=``. :param assertion: some value to evaluate for truth-ness :param message: optional message used for raising AssertionError """

    message = message or assertion

    if not assertion:
        raise AssertionError(message)

    return True