title: span<T> and streams
body: <p>I have been reading about span for a while now, and just tried to implement it. However, while I can get span to work I cannot figure out how to get a stream to accept it like they do in the examples. Other examples show int.parse supporting spans as well but I can't find overloads or extensions that make it possible.</p>
  <p>I have tried it in both <code>.net standard 2.0</code> and <code>.net core 2.0</code></p>
  <p>Please point me in the right direction to make this work.</p>
  <p><strong>Code example</strong></p>
  <pre><code>Span&lt;Byte&gt; buffer = new Span&lt;byte&gt;();
  int bytesRead = stream.Read(buffer);
  </code></pre>