te subtree.
          const newedge = net.linkVertexes(parent, subst, null);
        }
      }
      return net;
    }

    assignTreeVertexValues(v) {
      // if a vertex has any assistants, use Bus alignment
      let any = false;
      const children = v.children;
      for (let i = 0; i < children.length; i++) {
        const c = children[i];
        if (isAssistant(c.node)) {
          any = true;
          break;
        }
      }
      if (any) {
        // this is the parent for the assistant(s)
  