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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 add_linear_constraints(self, *relations):
 """Add constraints to the problem Each constraint is represented by a Relation, and the expression in that relation can be a set expression. """

        constraints = []

        for relation in relations:
            if self._check_relation(relation):
                constraints.append(Constraint(self, None))
            else:
                for name in self._add_constraints(relation):
                    constraints.append(Constraint(self, name))

        return constraints