code: def get_uid(brain_or_object):
      
      if is_portal(brain_or_object):
          return '0'
      if is_brain(brain_or_object) and base_hasattr(brain_or_object, "UID"):
          return brain_or_object.UID
      return get_object(brain_or_object).UID()
docs: Get the Plone UID for this object
  
      :param brain_or_object: A single catalog brain or content object
      :type brain_or_object: ATContentType/DexterityContentType/CatalogBrain
      :returns: Plone UID
      :rtype: string