def activity_type_exists(activity_type):
 if (activity_type in object_id_validators):
  return activity_type
 else:
  raise Invalid(('%s: %s' % (_('Not found'), _('Activity type'))))

def activity_type_exists ( activity_type ) : if ( activity_type in object_id_validators ) : return activity_type else : raise Invalid ( ( '%s: %s' % ( _ ( 'Not found' ) , _ ( 'Activity type' ) ) ) )
raises invalid if there is no registered activity renderer for the given activity_type .