/**
 * A more composable version of https://www.npmjs.com/package/promise-inflight.
 *
 * @param {Function}
 *        A unary, promise-returning function.
 * @returns {Function}
 *        A version of the given function which batches together calls for the
 *        the same input value.
 */
export default function batchConcurrent<T, N>(fn: (input: T) => Promise<N>): (input: T) => Promise<N>;