code: def get_modification_date(brain_or_object):
      
      modified = getattr(brain_or_object, "modified", None)
      if modified is None:
          fail("Object {} has no modification date ".format(
               repr(brain_or_object)))
      if callable(modified):
          return modified()
      return modified
docs: Get the modification date of the brain or object
  
      :param brain_or_object: A single catalog brain or content object
      :type brain_or_object: ATContentType/DexterityContentType/CatalogBrain
      :returns: Modification date
      :rtype: DateTime