old_contents: import {EventEmitter} from 'events';
  import {System} from './system';
  
  export class Nextion extends EventEmitter {
    constructor (uart) {
      super();
  
      if (!uart) {
        throw new TypeError('"uart" must be a UART instance');
      }
      this.uart = uart.bind()
        .on('event', (...args) => {
          this.emit('event', ...args);
        });
  
      this.system = new System(uart);
    }
  
    async setValue (variableName, value) {
      return await this.uart.setValue(variableName, value);
    }
  
    async setComponentValue (componentName, value) {
      return await this.setVariableValue(`${componentName}.val`, value);
    }
  }
  
  Nextion.prototype.setVariableValue = Nextion.prototype.setValue;
  
new_contents: import {EventEmitter} from 'events';
  import {System} from './system';
  import debug from 'debug';
  
  const nDebug = debug('nextion:Nextion');
  
  export class Nextion extends EventEmitter {
    constructor (uart) {
      super();
  
      if (!uart) {
        throw new TypeError('"uart" must be a UART instance');
      }
      this.uart = uart.bind()
        .on('event', (...args) => {
          this.emit('event', ...args);
        });
  
      this.system = new System(uart);
  
      nDebug('Nextion ready');
    }
  
    async setValue (variableName, value) {
      return await this.uart.setValue(variableName, value);
    }
  
    async setComponentValue (componentName, value) {
      return await this.setVariableValue(`${componentName}.val`, value);
    }
  }
  
  Nextion.prototype.setVariableValue = Nextion.prototype.setValue;
  
subject: add a debug