code: function inarray (list, item) {
    list = Object.prototype.toString.call(list) === '[object Array]' ? list : []
  
    var idx = -1
    var end = list.length
  
    while (++idx < end) {
      if (list[idx] === item) return true
    }
  
    return false
  }
docs: Whether given value exists in array.
  
  @param {Array} list
  The list to search.
  
  @param {*} item
  The item/value to search for.
  
  @return {Boolean}
  Whether given value exists in array.