docs: def delete_cas(self, key, *, index):
          """Deletes the Key with check-and-set semantics.
  
          Parameters:
              key (str): Key to delete
              index (ObjectIndex): Index ID
  
          The Key will only be deleted if its current modify index matches
          the supplied Index
          """
          self.append({
              "Verb": "delete-cas",
              "Key": key,
              "Index": extract_attr(index, keys=["ModifyIndex", "Index"])
          })
          return self