code: function listenersHelp (element, events, handler, method) {
    let list = events.split(' ')
    for (let i = 0, len = list.length; i < len; i++) {
      let item = list[i]
      if (method === false) {
        element.removeEventListener(item, handler)
      } else {
        element.addEventListener(item, handler, false)
      }
    }
  }
docs: Add or remove listeners from an element.
  
  @inner
  @param {HTMLElement} element element
  @param {string} events Events' name that are splitted by space
  @param {Function} handler Event handler
  @param {?boolean} method Add or remove.