You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: rateable.rb
    path of file: ./repos/mongoid_rateable/lib/mongoid_rateable
    
    the code of the file until where you have to start completion: module Mongoid
  module Rateable
    ex
    
    def unrate(rater)
      case rater
      when Array
        rater.each{|rater| unrate(mark, rater, weight)}
      else
        unrate_without_rating_update(rater)
        update_rating
      end