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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 lp7(self, reaction_subset):
 """Approximately maximize the number of reaction with flux. This is similar to FBA but approximately maximizing the number of reactions in subset with flux > epsilon, instead of just maximizing the flux of one particular reaction. LP7 prefers "flux splitting" over "flux concentrating". """


        if self._zl is None:
            self._add_maximization_vars()

        positive = set(reaction_subset) - self._flipped
        negative = set(reaction_subset) & self._flipped

        v = self._v.set(positive)
        zl = self._zl.set(positive)
        cs = self._prob.add_linear_constraints(v >= zl)
        self._temp_constr.extend(cs)

        v = self._v.set(negative)
        zl = self._zl.set(negative)
        cs = self._prob.add_linear_constraints(v <= -zl)
        self._temp_constr.extend(cs)

        self._prob.set_objective(self._zl.sum(reaction_subset))

        self._solve()