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: differ.rb
    path of file: ./repos/differ/lib
    
    the code of the file until where you have to start completion: require 'differ/change'
require 'differ/diff'
require 'differ/format/ascii'
require 'differ/format/color'
require 'differ/format/html'

module Differ
  class << self

    def diff(target, source, separa
    
    def diff(target, source, separator = "\n")
      old_sep, $; = $;, separator

      target = target.split(separator)
      source = source.split(separator)

      $; = '' if separator.is_a? Regexp

      @diff = Diff.new
      advance(target, source) until source.empty? || target.empty?
      @diff.insert(*target) || @diff.delete(*source)
      return @diff
    ensure
      $; = old_sep
    end