removeEdge(src, dest) {

  const srcDestIdx = this.adjacencyList.get(src).indexOf(dest);

  this.adjacencyList.get(src).splice(srcDestIdx, 1);

​

  const destSrcIdx = this.adjacencyList.get(dest).indexOf(src);

  this.adjacencyList.get(dest).splice(destSrcIdx, 1);

}