def template_filter(self, name=None):
        """A decorator that is used to register custom template filter.
        You can specify a name for the filter, otherwise the function
        name will be used. Example::

          @app.template_filter()
          def reverse(s):
              return s[::-1]

        :param name: the optional name of the filter, otherwise the
                     function name will be used.
        """
        def decorator(f):
            self.add_template_filter(f, name=name)
            return f
        return decorator
A decorator that is used to register custom template filter.
        You can specify a name for the filter, otherwise the function
        name will be used. Example::

          @app.template_filter()
          def reverse(s):
              return s[::-1]

        :param name: the optional name of the filter, otherwise the
                     function name will be used.