code: function _getTripByDeparture(db, originId, destinationId, departure, callback) {
  
    // Get Effective Services for departure date
    _buildEffectiveServiceIDString(db, departure.getDateInt(), function(err, serviceIdString) {
      if ( err ) {
        return callback(err);
      }
  
      // Find a matching trip
      _getMatchingTripId(db, originId, destinationId, departure, serviceIdString, function(err, tripId) {
        if ( err ) {
          return callback(err);
        }
  
        // --> No matching trip found
        if ( tripId === undefined ) {
          return callback(null, undefined);
        }
  
        // Build the matching trip...
        getTrip(db, tripId, departure.getDateInt(), function(err, trip) {
          if ( err ) {
            return callback(err);
          }
  
          // --> Return the matching trip
          return callback(err, trip);
  
        });
  
      });
  
    });
  
  }
docs: Get the Trip that matches the origin, destination and departure information
  @param {RightTrackDB} db The Right Track DB to query
  @param {string} originId Origin Stop ID
  @param {string} destinationId Destination Stop ID
  @param {DateTime} departure Departure DateTime
  @param {function} callback getTrip callback function(err, trip)
  @private