title: rethinkdb with filter and getNearest commands
body: <p>How can execute getNearest query about the result of other command, for example a filter command?</p>
  
  <pre><code>var point = r.point(-122.422876,37.777128);  
  r.db('test').table('users').
     filter({tags : 'tag'}).
     getNearest(point, {index: 'geodata', maxResults: 30, unit :'km'})
  </code></pre>
  
  <p>I have a 'users' table:</p>
  
  <pre><code> [ 
     {id: 1, tags : ['music', 'cups'], geodata: r.point()} 
     {id: 2, tags: ['music', 'play'], geodata: r.point()} 
   ] 
  </code></pre>
  
  <p>First I want to filter by 'tags' field and then return the nearest. </p>
  
  <p>The query that I have specified is incorrect, return the follow error: "<strong>RqlRuntimeError: Expected type TABLE but found SELECTION</strong>"</p>