import type { OmitStrict } from './types.js';
/**
 * Returns a boolean indicating if `value` is
 * a plain object, possibly created with `Object.create(null)`.
 * But warning! This fails for some obscure corner cases, use a proper library for weird things.
 */
export declare const is_plain_object: (value: any) => boolean;
/**
 * Iterated keys in `for..in` are always returned as strings,
 * so to prevent usage errors the key type of `mapper` is always a string.
 * Symbols are not enumerable as keys, so they're excluded.
 */
export declare const map_record: <T, K extends string | number, U>(obj: Record<K, T>, mapper: (value: T, key: string) => U) => Record<K, U>;
/**
 * Creates a new object without the specified `keys`.
 */
export declare const omit: <T extends Record<K, any>, K extends keyof T>(obj: T, keys: Array<K>) => OmitStrict<T, K>;
/**
 * Creates a new object with properties that pass the `should_pick` predicate.
 */
export declare const pick_by: <T extends Record<K, any>, K extends string | number>(obj: T, should_pick: (value: any, key: K) => boolean) => Partial<T>;
/**
 * A commonly used form of `pick_by`.
 *
 * @returns `obj` with all `undefined` properties removed
 *
 * @see {@link https://github.com/Microsoft/TypeScript/issues/13195}
 */
export declare const omit_undefined: <T extends Record<string | number, any>>(obj: T) => T;
/**
 * A more explicit form of `{put_this_first: obj.put_this_first, ...obj}`.
 */
export declare const reorder: <T extends Record<K, any>, K extends string | number>(obj: T, keys: Array<K>) => T;
/**
 * Frozen empty object with no properties, good for options default values.
 */
export declare const EMPTY_OBJECT: Record<string | number | symbol, undefined> & object;
/**
 * Performs a depth-first traversal of an object's enumerable properties,
 * calling `cb` for every key and value with the current `obj` context.
 * @param cb - receives the key, value, and `obj` for every enumerable property on `obj` and its descendents
 */
export declare const traverse: (obj: any, cb: (key: string, value: any, obj: any) => void) => void;
export declare const transform_empty_object_to_undefined: <T>(obj: T) => T | undefined;
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