/**
 * @name distance
 * @summary Returns the distance between two points.
 *
 * @description Returns the distance between two points in a cartesian plane.
 *
 * @example
 * // Normal usage
 * let result = distance(2,4,6,8);
 * // => 2.8284271247461903
 *
 * @param {number} x1
 * @param {number} x2
 * @param {number} y1
 * * @param {number} y2
 * @returns {number} the resulting distance.
 *
 * @function pure
 */
export default function distance(x1: number, x2: number, y1: number, y2: number): number;