code: function (globe, positions, position, followTerrain) {
                  var elevation = position.altitude;
                  if (followTerrain) {
                      elevation = globe.elevationAtLocation(position.latitude, position.longitude);
                  }
                  positions.push(new Position(position.latitude, position.longitude, elevation));
                  return positions;
              }
docs: Adds a position to a list of positions.
  If the path is following the terrain the elevation is also computed.
  
  @param {Globe} globe
  @param {Position[]} positions The list of positions to add to
  @param {Position} position The position to add to the list
  @param {Boolean} followTerrain
  
  @return {Position[]} The list of positions