handleRemoveElements({ nodes, edges }) {

    if (nodes.length) {
      // the adapter also removes edges when nodes are removed.
      this.handleRemoveNodes(nodes);

    } else if (edges.length) {
      this.handleRemoveEdges(edges);

    }

    this.resetVisManipulationBar();


  }
Called by vis when the user tries to delete nodes or edges.
The action is delegated to subhandlers.

@param {Array<Id>} nodes - Removed edges.
@param {Array<Id>} edges - Removed nodes.