def ok_response(asset, env)
        if head_request?(env)
          [ 200, headers(env, asset, 0), [] ]
        else
          [ 200, headers(env, asset, asset.length), asset ]
        end
      end
def ok_response(asset, env)
        if head_request?(env)
          [ 200, headers(env, asset, 0), [] ]
        else
          [ 200, headers(env, asset, asset.length), asset ]
        end
      end
Returns a 200 OK response tuple