code: def export_gpx_file(self):
          
          gpx = create_elem('gpx', GPX_ELEM_ATTRIB)
          if not self.metadata.bounds:
              self.metadata.bounds = self[:]
          gpx.append(self.metadata.togpx())
          for place in self:
              gpx.append(place.togpx())
  
          return etree.ElementTree(gpx)
docs: Generate GPX element tree from ``Waypoints`` object.
  
          Returns:
              etree.ElementTree: GPX element tree depicting ``Waypoints`` object