code: function (clss, el) {
    if (isString(clss)) classList(el).add(clss)
    if (isObject(clss)) {
      var classArr = el.className.split(' ')
      var key
      for (key in clss) {
        if (classArr.indexOf(key) && clss[key] === false) classList(el).remove(key)
        if (clss.hasOwnProperty(key) && clss[key] === true) classList(el).add(key)
      }
    }
    if (isArray(clss)) {
      var i
      for (i = 0;i < clss.length; i++) {
        classList(el).add(clss[i])
      }
    }
  }
docs: (clss → string | object | array, el → dom)
  - add and remove class of element