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: query_parser.rb
    path of file: ./repos/truffleruby/bench/sinatra/bundle/gems/rack-2.2.3/lib/rack
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Rack
  class QueryParser
    (require_relative 'core_ext/regexp'; using ::Rack::RegexpExtensions) if RUBY_VERSION < '2.4'

    DEFAULT_SEP = /[&;] */n
    COMM
    
    def parse_query(qs, d = nil, &unescaper)
      unescaper ||= method(:unescape)

      params = make_params

      (qs || '').split(d ? (COMMON_SEP[d] || /[#{d}] */n) : DEFAULT_SEP).each do |p|
        next if p.empty?
        k, v = p.split('=', 2).map!(&unescaper)

        if cur = params[k]
          if cur.class == Array
            params[k] << v
          else
            params[k] = [cur, v]
          end
        else
          params[k] = v
        end