Lodash

Hi guys. This keeps returning fail whenever I run the test on the code below. _,clamp id defined - failed: _.clamp() was not properly defined is the error.
Anyone with useful tip to correct it? Cheers all

const _ = {

clamp(number, lower, upper){

 var lowerClampedValue = Math.max(number, lower);

  var clampedValue = Math.min(lowerClampedValue, upper);

  return clampedValue;

https://www.codecademy.com/paths/full-stack-engineer-career-path/tracks/fscp-javascript-syntax-part-ii/modules/fecp-practice-javascript-syntax-arrays-loops-objects-iterators/projects/lodash