比如下面这个例子（看得我头昏眼花）
TopologyList[Process -> {F[1, {1}]} -> {F[1, {1}]}, Model -> {"QED"},
GenericModel -> {"Lorentz"}, InsertionLevel -> {Generic, Classes},
ExcludeParticles -> {}, ExcludeFieldPoints -> {},
LastSelections -> {}][
Topology[2][
Propagator[Incoming][Vertex[1][1], Vertex[3][3], Field[1]],
Propagator[Outgoing][Vertex[1][2], Vertex[3][3], Field[2]],
Propagator[Internal][Vertex[3][3], Vertex[3][4], Field[3]],
Propagator[Loop[1]][Vertex[3][4], Vertex[3][4], Field[4]]] ->
Insertions[Generic][
FeynmanGraph[2, Generic == 1][Field[1] -> F[1, {1}],
Field[2] -> -F[1, {1}], Field[3] -> V, Field[4] -> F] ->
Insertions[Classes][
FeynmanGraph[1, Classes == 1][Field[1] -> F[1, {1}],
Field[2] -> -F[1, {1}], Field[3] -> V[1], Field[4] -> -F[1, {
SequenceForm["Gen", 3]}]]]],
Topology[2][
Propagator[Incoming][Vertex[1][1], Vertex[3][3], Field[1]],
Propagator[Outgoing][Vertex[1][2], Vertex[3][4], Field[2]],
Propagator[Loop[1]][Vertex[3][3], Vertex[3][4], Field[3]],
Propagator[Loop[1]][Vertex[3][3], Vertex[3][4], Field[4]]] ->
Insertions[Generic][
FeynmanGraph[1, Generic == 1][Field[1] -> F[1, {1}],
Field[2] -> -F[1, {1}], Field[3] -> F, Field[4] -> V] ->
Insertions[Classes][
FeynmanGraph[1, Classes == 1][Field[1] -> F[1, {1}],
Field[2] -> -F[1, {1}], Field[3] -> F[1, {1}],
Field[4] -> V[1]]]]]
TreeForm给出一团糟