def additional_context():
    if request.endpoint != fn.__name__:
        return {}
var1, var2, var3 = generate_sidebar_data()
return {'var1': var1, 'var2': var2, 'var3': var3}
return fn

@blueprint.route('/')
@include_sidebar_data
def frontpage():
    return render_template('template.html')
How can I send variables to Jinja template from a Flask decorator?