attached(...params) {
    let args = params;
    if (!args.length) { args = ['in']; }
    /** @type {Array<Array<number>>} */
    const res = [];
    args.forEach((port) => {
      if (!this.ports.ports[port]) {
        throw new Error(`Node ${this.nodeInstance.nodeId} has no port '${port}'`);
      }
      res.push(this.ports.ports[port].listAttached());
    });
    if (args.length === 1) {
      return res[0];
    }
    return res;
  }
@param {...string} params - Port names to check for attachment
@returns {Array<number> | Array<Array<number>>}