declare module 'periscope-data' {
  export class Query implements IQuery {
    fields: string[];
    filter: string;
    skip: int32;
    take: int32;
    sort: string;
    sortDir: string;
    cacheKey(): string;
  }
  
  // implements IDataSource interface
  export class DataSource implements IDataSource {
    constructor(name: string);
    name: string;
    configuration: IDataSourceConfiguration;
    getDataHolder(query: IQuery): Promise<IDataHolder>;
    update(id: string, entity: any): Promise;
    create(entity: any): Promise<string>;
    
    // returnes an id of new created instance
    delete(id: string): Promise;
  }
  export class DataHolder implements IDataHolder {
    constructor();
    query: IQuery;
    total: int32;
    data: array<any>;
  }
}