title: How can I extend Node's stream
body: <p>I'm trying to create a method for Readable Stream, but after trying just a little bit, I ran out of ideas to how.</p>
  
  <pre><code>import * as stream from 'stream'
  //yields Property 'asdasas' does not exists on type 'Readable'
  stream.Readable.prototype.asdasas 
  //yields asdas does not exists on type 'typeof Readable'
  stream.Readable.asdas
  </code></pre>
  
  <p>Can someone give me a solution and explain why the errors happened? Thanks</p>