code: function next() {
  		var u;
  		if ( count === len ) {
  			debug( 'Finished all queries.' );
  			out.meta.success = scount;
  			out.meta.failure = fcount;
  			return clbk( null, out, ratelimit );
  		}
  		if ( idx < len ) {
  			u = users[ idx ];
  			debug( 'Querying for username: `%s` (%d).', u, idx );
  			opts.pathname = '/users/' + u;
  			request( opts, onResponse( u, idx ) );
  			idx += 1;
  		}
  	}
docs: FUNCTION: next()
  Requests user details data for the next username in the queue. Once requests for all desired usernames have completed, invokes the provided callback.
  
  @private
  @returns {Void}