Look and Say!

This is a codecheck challenge. To get started, see the docs :-)

The look and say method is a secret method that returns the below results:

If this method receives '1', it should return '1'. If it receives '2', it should return '11'.
If it receives '3', it should return '21', and so on.

1 -> 1
2 -> 11
3 -> 21
4 -> 1211
5 -> 111221
6 -> 312211
7 -> 13112221

Your Mission

Identify the rule of this sequence and implement the function.

Build the solution as a CLI application.
Input parameters will be passed as an argument of CLI, and the output should be written to stdout.

You can use the following languages to solve this challenge.

How to make a CLI application with each language is explained in [YOUR LANGUAGE].md

You can see 7 testcases in testcase.js. However, this challenge has 3 additional hidden testcases:

SecretTest1. Passes an integer of '8', and expects a correct answer.
SecretTest2. Passes an integer of '20', and expects a correct answer.
SecretTest3. Passes an integer of '10000'. Find the initial 500 digits of the expected output, and write this in the first line of answer.md. Explain how you solved the problem beginning from line 2.

If your function is implemented correctly, the first 2 tests will pass.

However, if your implementation is too earnest, the last question will eat up all of your memory! :( Try to find a way to optimize.

PS: The secret tests will run only when the challenge is submitted, and the results are never shown in the WebEditor.

In answer.md write a brief explanation about: