code: func (ctx *RequestCtx) SetBodyStream(bodyStream io.Reader, bodySize int) {
  	ctx.Response.SetBodyStream(bodyStream, bodySize)
  }
docs: // SetBodyStream sets response body stream and, optionally body size.
  //
  // bodyStream.Close() is called after finishing reading all body data
  // if it implements io.Closer.
  //
  // If bodySize is >= 0, then bodySize bytes must be provided by bodyStream
  // before returning io.EOF.
  //
  // If bodySize < 0, then bodyStream is read until io.EOF.
  //
  // See also SetBodyStreamWriter.