ded either as a non-negative integer code, or as a character:
"Tram", "Train", "Bus", "Vline" or "Night Bus". Character inputs are not
case-sensitive. Use the <code><a href='route_types.html'>route_types</a></code> function to extract a
vector of all route types.</p></td>
    </tr>
    <tr>
      <th>stop_id</th>
      <td><p>Integer. Optionally filter results to a specific stop ID.
These can be searched for with the <code>stops_on_route</code> and <code>stops_nearby</code>
functions.</p></td>
    </tr>
   