Vertex: 
  v1: {label: Hello}
  v2: {label: GRINEdit}
  v3: {}
  v4: {classname: CircleVertex, params: {}}
Edge: 
  e1: [v1, v2]
  e2: {classname: TriangleEdge, params: [v2, v3]}
  e3: [v3, v4]
