title: how to use superagent-proxy?
body: <p>I find it hard to use <a href="https://github.com/TooTallNate/superagent-proxy" rel="nofollow noreferrer">superagent-proxy</a>, just with the simple code:</p>
  
  <pre><code>const superagent = require('superagent')
  require('superagent-proxy')(superagent)
  
  let proxy = 'http://221.237.122.22:8118' // 设置代理
  
  superagent
    .get('http://sf.gg')
    .proxy(proxy)
    .timeout(3600*1000)
    .end((err, res) =&gt; {
      console.log(res)
      console.log(res.status, res.headers);
      console.log(res.body);
    })
  </code></pre>
  
  <p>but when run, it cannot get an reply, why?</p>