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: servlet.rb
    path of file: ./repos/rdoc/lib/rdoc
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
require_relative '../rdoc'
require 'erb'
require 'time'
require 'json'

begin
  require 'webrick'
re
    
  def asset generator_name, req, res
    asset_dir = @asset_dirs[generator_name]

    asset_path = File.join asset_dir, req.path

    if_modified_since req, res, asset_path

    res.body = File.read asset_path

    res.content_type = case req.path
                       when /\.css\z/ then 'text/css'
                       when /\.js\z/  then 'application/javascript'
                       else                'application/octet-stream'
                       end