title: "Carry" value to next .map
body: <p>Maybe the title is misleading. Please change at will.</p>
  
  <p>I have an Observable (Subject) which emits a value. I want to pass this value to generate a new observable (via flatMap) but also pass it down to the flatMap's operation:</p>
  
  <pre><code>getAddressSubject
       .flatMap(latLng -&gt; getApiManagerInstance().getAddress(latLng))
       .map(addressResponse -&gt;{
            // here I want to use both latLng and addressResponse
            // e.g:
           createObject(latLng, addressResponse);
       })
  </code></pre>