code: def set(
      self, credentials: SyftVerifyKey, oblv_keys: OblvKeys
  ) -> Result[OblvKeys, Err]:
      if not len(self):
          valid = self.check_type(oblv_keys, self.object_type)
          if valid.is_err():
              return SyftError(message=valid.err())
  
          return super().set(credentials, oblv_keys)
      else:
          return Err(
              "Domain Node already has an existing public/private key pair"
          )
  
imports: from typing import Any
  from typing import Optional
  from result import Err
  from result import Ok
  from result import Result
  from ...node.credentials import SyftVerifyKey
  from ...serde.serializable import serializable
  from ...service.response import SyftError
  from ...store.document_store import BaseStash
  from ...store.document_store import DocumentStore
  from ...store.document_store import PartitionSettings
  from ...store.document_store import QueryKeys
  from ...store.document_store import UIDPartitionKey
  from ...types.uid import UID
  from .oblv_keys import OblvKeys
label_desc: Use image node_id 3 for calling the OblvKeysStash obj's underlying member method code with example usage: obj.set(credentials, oblv_keys) and returns: super, Err, SyftError