func setUpCoupling() coupling.Coupling {
c := coupling.New()
n1 := coupling.Node{S: 0, T: 0}
n2 := coupling.Node{S: 0, T: 1}
n3 := coupling.Node{S: 1, T: 0}
n4 := coupling.Node{S: 1, T: 1}
e1 := coupling.Edge{&n1, 0.5, true}
e2 := coupling.Edge{&n2, 0.2, true}
e3 := coupling.Edge{&n3, 0, false}
e4 := coupling.Edge{&n4, 0.3, true}
n1.Succ = []*coupling.Node{&n1, &n2, &n4}
n2.Succ = []*coupling.Node{&n2, &n4, &n1}
n4.Succ = []*coupling.Node{&n2, &n1, &n4}
n2.Adj = [][]*coupling.Edge{[]*coupling.Edge{&e1, &e2}, []*coupling.Edge{&e3, &e4}}
c.Nodes = []*coupling.Node{&n1, &n2, &n3, &n4}
return c
}
