text: function fourNumberSum(array, targetSum) {
      let i, j, k, l;
      let res = [];
      let sum = 0;
      
      //Brute force approach, try all the possible sums with the four possible numbers, without repeating
      //and if there is a coincidence, it will push it into res array.
      for(i=0; i<array.length; i++){
          for(j=i+1; j<array.length; j++){
              for(k=j+1; k<array.length; k++){
                  for(l=k+1; l<array.length; l++){
                      sum = array[i] + array[j] + array[k] + array[l];
                      if(sum == targetSum) res.push([array[i], array[j], array[k], array[l]]);
                  }
              }
          }
      }
  
      return res;
  }//End of fourNumberSum
  
  fourNumberSum([7, 6, 4, -1, 1, 2], 16);
  fourNumberSum([-2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9], 4);
  fourNumberSum([-10, -3, -5, 2, 15, -7, 28, -6, 12, 8, 11, 5], 20);
  