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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 constraints_since(self, other):
 """ Returns the constraints that have been accumulated since `other`. :param other: a prior PathHistory object :returns: a list of constraints """


        constraints = [ ]
        cur = self
        while cur is not other and cur is not None:
            constraints.extend(cur.recent_constraints)
            cur = cur.parent
        return constraints