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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 _collapse_postconditions(base_postconditions: List[Contract], postconditions: List[Contract]) -> List[Contract]: """ Collapse function postconditions with the postconditions collected from the base classes. :param base_postconditions: postconditions collected from the base classes :param postconditions: postconditions of the function (before the collapse) :return: collapsed sequence of postconditions """

    return base_postconditions + postconditions