code: def navigation(self, id=None):
          
  
          def wrapper(f):
              self.register_element(id or f.__name__, f)
              return f
  
          return wrapper
docs: Function decorator for navbar registration.
  
          Convenience function, calls :meth:`.register_element` with ``id`` and
          the decorated function as ``elem``.
  
          :param id: ID to pass on. If ``None``, uses the decorated functions
                     name.