code: function add(values, value) {
    var self = this
  
    if (value) {
      self.map[values] = value
    } else {
      addAll(self.map, values)
    }
  
    return self
  }
docs: /* Add values to map.
  When the second argument is given, it is treated as
  a single value and the first parameter as a key.
  Otherwise, every value in the first argument is added.