code: def init_app(self, app):
          
          self.init_config(app)
  
          # Install datetime helpers.
          app.jinja_env.filters.update(
              from_isodate=from_isodate,
              from_isodatetime=from_isodatetime,
              to_arrow=to_arrow,
              format_arrow=format_arrow,
          )
  
          if app.config['FORMATTER_BADGES_ENABLE']:
              from invenio_formatter.context_processors.badges import \
                  badges_processor
  
              # Registration of context processors.
              app.context_processor(badges_processor)
              # Register blueprint.
              app.register_blueprint(create_badge_blueprint(
                  app.config['FORMATTER_BADGES_ALLOWED_TITLES']))
  
          app.extensions['invenio-formatter'] = self
docs: Flask application initialization.
  
          :param app: The Flask application.