title: How to disable the "Expect: 100 continue" header in HttpWebRequest for a single request?
body: <p><code>HttpWebRequest</code> automatically appends an <code>Expect: 100-continue</code> header for POST requests. Various sources around the internet suggest that this can be disabled as follows:</p>
  
  <pre><code>System.Net.ServicePointManager.Expect100Continue = false;
  </code></pre>
  
  <p>However, I'm writing a library and I cannot disable this for the entire appdomain, in case the application relies on this behaviour. Nor can I assume that it will remain set to this value. How can I disable it for a specific request?</p>