on(eventName, callback) {
    if (this.lsf && eventName.startsWith("lsf:")) {
      const evt = toCamelCase(eventName.replace(/^lsf:/, ""));

      this.lsf?.lsfInstance?.on(evt, callback);
    }

    const events = this.getEventCallbacks(eventName);

    events.add(callback);
    this.callbacks.set(eventName, events);
  }
Assign an event handler
@param {string} eventName
@param {Function} callback