import React from 'react';
/**
 * Maps an array, skipping the value if `fn` returns `undefined`.
 *
 * @example mapMaybe(array, fn) ≡ array.map(fn).filter(v => v !== undefined)
 */
export declare function mapMaybe<T, U>(array: T[], fn: (value: T, index: number) => U | undefined): U[];
/**
 * Insert a separator between each element of the array.
 *
 * @example intersperse(',', ['a', 'b', 'c']) ≡ ['a', ',', 'b', ',' 'c']
 */
export declare function intersperse<T>(separator: T, array: T[]): T[];
export declare function isWhitespace(node: React.ReactNode): boolean;
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