#!/usr/bin/env python3
# -*- coding: utf-8 -*-

from io import BytesIO

# write to BytesIO:
f = BytesIO()
f.write(b"hello")
f.write(b" ")
f.write(b"world!")
print(f.getvalue())

# read from BytesIO:
data = "人闲桂花落，夜静春山空。月出惊山鸟，时鸣春涧中。".encode("utf-8")
f = BytesIO(data)
print(f.read())