var groupVertices: [Vertex] = []
let vertexIdString = String(line[Range(match.range(at: 2), in: line)!])
let vertexIds = vertexIdString.split(separator: ",", omittingEmptySubsequences: true).map(
var groupVertices: [Vertex] = []
let vertexIdString = String(line[Range(match.range(at: 2), in: line)!])
let vertexIds = vertexIdString.split(separator: ",", omittingEmptySubsequences: true).map(