export function atan(x: number): number {
  //      discuss at: https://locutus.io/python/atan/
  // parity verified: Python 3.12
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Returns the arc tangent of x, in radians
  //       example 1: atan(0)
  //       returns 1: 0
  //       example 2: atan(1)
  //       returns 2: 0.7853981633974483
  //       example 3: atan(-1)
  //       returns 3: -0.7853981633974483

  return Math.atan(x)
}