def METHOD_NAME():
    # Test vector variables and sums
    rp = pyo.TransformationFactory("replace_variables")
    m = pyo.ConcreteModel()
    m.x = pyo.Var(["a", "b", "c"], initialize=2)
    m.y = pyo.Var(initialize=3)
    m.z = pyo.Var(initialize=0)
    m.c1 = pyo.Constraint(expr=m.z == m.x["a"] + m.x["b"] + m.x["c"])
    m.e1 = pyo.Expression(expr=sum(m.x[i] for i in m.x))
    assert m.c1.body() == -6  # hope constraint arrangement is deterministic
    assert pyo.value(m.e1) == 6
    rp.apply_to(m, substitute=[(m.x["c"], m.y)])
    assert m.c1.body() == -7
    assert pyo.value(m.e1) == 7