code: func (ctx *RequestCtx) SetUserValueBytes(key []byte, value interface{}) {
  	ctx.userValues.SetBytes(key, value)
  }
docs: // SetUserValueBytes stores the given value (arbitrary object)
  // under the given key in ctx.
  //
  // The value stored in ctx may be obtained by UserValue*.
  //
  // This functionality may be useful for passing arbitrary values between
  // functions involved in request processing.
  //
  // All the values stored in ctx are deleted after returning from RequestHandler.