如何在cplex python中编码子回路约束

import cplex

# 创建cplex问题对象
problem = cplex.Cplex()

# 定义变量
problem.variables.add(names=["x1", "x2", "x3"], types=[problem.variables.type.binary]*3)

# 添加目标函数
problem.objective.set_sense(problem.objective.sense.minimize)
problem.objective.set_linear([1, 2, 3], ["x1", "x2", "x3"])

# 添加子回路约束
problem.linear_constraints.add(lin_expr=[cplex.SparsePair(ind=["x1", "x2", "x3"], val=[1, 1, 1])], senses=["E"], rhs=[1])

# 求解问题
problem.solve()

# 获取最优解
solution = problem.solution.get_values()