title: StructureMap singleton
body: <p>Are these two equivalent?</p>
  
  <p>1)          var store = new DocumentStore();</p>
  
  <pre><code>        For&lt;IDocumentStore&gt;().Use(store);
  </code></pre>
  
  <p>2)          var store = new DocumentStore();</p>
  
  <pre><code>        For&lt;IDocumentStore&gt;().Singleton().Use(store);
  </code></pre>
  
  <p>or        </p>
  
  <pre><code>        For&lt; IDocumentStore&gt;().AlwaysUnique().Use(store);
  </code></pre>
  
  <p>Will both of these return singleton instance of documentstore with no duplicate instances?</p>