code: function remove(keys) {
    var self = this
  
    if (typeof keys === 'string') {
      self.map[keys] = undefined
    } else {
      removeAll(self.map, keys)
    }
  
    return self
  }
docs: /* Remove keys from 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.