// Solving the same problem from 04-File_System in Lecture_10 with Promise:
// Please note using Promise is the recommended option over using callbacks.
// See the original problem statement and its solution with callbacks at:
// https://sidp919.github.io/Web-Development/Lecture_10/04-File_System/index.html
// Q. there are two files: input1.txt and input2.txt
// both contain a list of numbers
// we need to get these lists of numbers and sort them
// then create output.txt and put the sorted combined list in output.txt
// A. see solution code using Promise at:
sort_promise.js
input1.txt
input2.txt
output.txt