class Rack::Runtime

def call(env)

def call(env)
  start_time = Utils.clock_time
  status, headers, body = @app.call(env)
  headers = Utils::HeaderHash[headers]
  request_time = Utils.clock_time - start_time
  unless headers.key?(@header_name)
    headers[@header_name] = FORMAT_STRING % request_time
  end
  [status, headers, body]
end