type MdKitBackendStore = {
  createCheckpoint?:   | MdKitDocumentVersionSummary
     | Promise<MdKitDocumentVersionSummary>;
  getLatestCheckpoint?:   | MdKitDocumentVersionDetail
     | Promise<
     | MdKitDocumentVersionDetail
     | null>
     | null;
  listDocumentVersions?:   | MdKitDocumentVersionSummary[]
     | Promise<MdKitDocumentVersionSummary[]>;
  readCollaborationState?:   | Uint8Array<ArrayBufferLike>
     | Promise<Uint8Array<ArrayBufferLike> | null>
     | null;
  readDocument:   | MdKitDocumentSnapshot
     | Promise<MdKitDocumentSnapshot>;
  readDocumentVersion?:   | MdKitDocumentVersionDetail
     | Promise<
     | MdKitDocumentVersionDetail
     | null>
     | null;
  resyncDocument?:   | MdKitDocumentSnapshot
     | Promise<MdKitDocumentSnapshot>;
  restoreDocumentVersion?:   | MdKitDocumentWriteResult
     | Promise<MdKitDocumentWriteResult>;
  writeCollaborationState?: void | Promise<void>;
  writeDocument:   | MdKitDocumentWriteResult
     | Promise<MdKitDocumentWriteResult>;
};

optional createCheckpoint(input: MdKitCreateCheckpointInput): 
  | MdKitDocumentVersionSummary
| Promise<MdKitDocumentVersionSummary>;

optional getLatestCheckpoint(documentId: string): 
  | MdKitDocumentVersionDetail
  | Promise<
  | MdKitDocumentVersionDetail
  | null>
  | null;

optional listDocumentVersions(documentId: string): 
  | MdKitDocumentVersionSummary[]
| Promise<MdKitDocumentVersionSummary[]>;

optional readCollaborationState(documentName: string): 
  | Uint8Array<ArrayBufferLike>
  | Promise<Uint8Array<ArrayBufferLike> | null>
  | null;

readDocument(documentId: string): 
  | MdKitDocumentSnapshot
| Promise<MdKitDocumentSnapshot>;

optional readDocumentVersion(input: {
  documentId: string;
  versionId: string;
}): 
  | MdKitDocumentVersionDetail
  | Promise<
  | MdKitDocumentVersionDetail
  | null>
  | null;

optional resyncDocument(documentId: string): 
  | MdKitDocumentSnapshot
| Promise<MdKitDocumentSnapshot>;

optional restoreDocumentVersion(input: MdKitRestoreDocumentVersionInput): 
  | MdKitDocumentWriteResult
| Promise<MdKitDocumentWriteResult>;

optional writeCollaborationState(documentName: string, state: Uint8Array): void | Promise<void>;

writeDocument(input: MdKitDocumentWriteInput): 
  | MdKitDocumentWriteResult
| Promise<MdKitDocumentWriteResult>;