title: How cast type when the original arg is a pointer
body: <p>So I have this:</p>
  
  <pre><code>v, ok := muxctx.Get(req, "req-body-map").(map[string]interface{})
  </code></pre>
  
  <p>the problem is that:</p>
  
  <pre><code>muxctx.Get(req, "req-body-map")
  </code></pre>
  
  <p>returns a pointer.  I tried dereferencing the pointer like so:</p>
  
  <pre><code>(*(muxctx.Get(req, "req-body-map"))
  </code></pre>
  
  <p>but I get this:</p>
  
  <pre><code>Invalid indirect of '(muxctx.Get(req, "req-body-map"))' (type 'interface{}') 
  </code></pre>
  
  <p>so I suppose since the Get method doesn't return a pointer, then I can't dereference it.</p>