/**
 * Compute the Haversine distance in kilometres based on longitude and latitude. The options (last parameter) are optional.
 *
 * @example
 * Basic usage
 *```js
 * const distance = distance(-73.66, 45.51, -79.43, 43.66, { decimals: 0 })
 * // returns 501
 * ```
 *
 * @param lon1 - Longitude of the first point
 * @param lat1 - Latitude of the first point
 * @param lon2 - Longitude of the second point
 * @param lat2 - Latitude of the second point
 * @param options - Optional parameter to specify the number of decimal places
 * @param options.decimals - The number of decimal places to keep in the result
 * @category Geo
 */
export default function distance(lon1: number, lat1: number, lon2: number, lat2: number, options?: {
    decimals?: number;
}): number;