code: func (b *ByteBuf) ReadBytes(n int) (int, []byte, error) {
  	data := make([]byte, n)
  	n, err := b.Read(data)
  	return n, data, err
  }
docs: // ReadBytes read bytes from buf
  // It's will copy the data to a new byte arrary
  // return readedBytesCount, byte array, error