text: 
  t = db.explain2
  t.drop();
  
  t.ensureIndex( { a : 1 , b : 1 } );
  
  for ( i=1; i<10; i++ ){
      t.insert( { _id : i , a : i , b : i , c : i } );
  }
  
  function go( q , c , b , o ){
      var e = t.find( q ).hint( {a:1,b:1} ).explain();
      assert.eq( c , e.n , "count " + tojson( q ) )
      /* NEW QUERY EXPLAIN
      assert.eq( b , e.nscanned , "nscanned " + tojson( q ) )
      */
      /* NEW QUERY EXPLAIN
      assert.eq( o , e.nscannedObjects , "nscannedObjects " + tojson( q ) )
      */
  }
  
  q = { a : { $gt : 3 } }
  go( q , 6 , 6 , 6 );
  
  q.b = 5
  go( q , 1 , 6 , 1 );
  
  delete q.b
  q.c = 5
  go( q , 1 , 6 , 6 );
  
  