title: Rx debounce operator with first and last
body: <p>Is there any combination of rx operators so as to get the first and last debounced event?</p>
  
  <p>This is going to be used in master detail scenarios (or even seach scenarios) where we want immediate loading of first selected item and the last after user stops changing selection.</p>
  
  <p>This would prevent the debounce time to be injected when the user navigates slowly but also prevent bursts of changes.</p>
  
  <p>If <a href="http://reactivex.io/documentation/operators/debounce.html" rel="noreferrer">debounce</a> operator had an option "immediate" like underscore.js <a href="http://underscorejs.org/#debounce" rel="noreferrer">debounce functoin</a> then a merge of the 2 versions of debounce operator would generate the needed result.</p>