import * as immutable from "immutable";
export declare function to_key(s: any): string;
export declare function to_str(obj: any[]): string;
export declare function map_merge_patch(obj1: any, obj2: any): {};
export declare function merge_set(obj: immutable.Map<any, any>, change: immutable.Map<any, any>): immutable.Map<any, any>;
export declare function nonnull_cols(f: immutable.Map<any, any>): immutable.Map<any, any>;