Function findMax

src/math/calculation.js:624–630

   */
  fn.max = function(...args) {
    const findMax = arr => {
      let max = -Infinity;
      for (let x of arr) {
        max = Math.max(max, x);
      }
      return max;
    };

    if (args[0] instanceof Array) {
      return findMax(args[0]);