/**
 * Collapse a list of Unix epoch intervals into the minimum set of non-overlapping intervals.
 *
 * - List-form generalization of `intervalUnionUnix`, which is pairwise only.
 * - Intervals are merged when they overlap or share an endpoint exactly (adjacent intervals
 *   ARE merged).
 * - Order of the input list does not matter; the result is sorted by start.
 * - Returns `[]` for an empty list.
 * - Returns `[]` when `intervals` is not an array, when any element is not a
 *   `{ start, end }` record of finite numeric (or numeric-string) values, or when any element
 *   has `start > end`.
 *
 * @param intervals array of `{ start, end }` records
 * @returns the minimum set of non-overlapping `{ start, end }` records, sorted by start, or `[]` on invalid input
 *
 * @example mergeIntervalsUnix([{ start: 0, end: 1000000 }, { start: 500000, end: 1500000 }]) // [{ start: 0, end: 1500000 }]
 * @example mergeIntervalsUnix([]) // []
 */
export declare function mergeIntervalsUnix(intervals: Array<{
    start: number | string;
    end: number | string;
}>): Array<{
    start: number;
    end: number;
}>;