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: content_length.rb
    path of file: ./repos/ferrocarril/mruby-gems/vendor/ruby/2.6.0/gems/rack-2.0.7/lib/rack
    
    the code of the file until where you have to start completion: require 'rack/utils'
require 'rack/body_proxy'

module Rack

  # Sets the Content-Length header on responses with fixed-length bodies.
  class ContentLength
    include Rack::Utils

    def initialize(app)
      @app = app
    end

    def call(env)
      status, headers, body =
    
    def call(env)
      status, headers, body = @app.call(env)
      headers = HeaderHash.new(headers)

      if !STATUS_WITH_NO_ENTITY_BODY.include?(status.to_i) &&
         !headers[CONTENT_LENGTH] &&
         !headers[TRANSFER_ENCODING] &&
         body.respond_to?(:to_ary)

        obody = body
        body, length = [], 0
        obody.each { |part| body << part; length += part.bytesize }

        body = BodyProxy.new(body) do
          obody.close if obody.respond_to?(:close)
        end

        headers[CONTENT_LENGTH] = length.to_s
      end