Check out example codes for "function should take three arguments - operation(string/char), value1(number), value2(number).". It will help you in understanding the concepts better.

Code Example 1

// TODO: Add your tests here
// Starting from Node 10.x, [Mocha](https://mochajs.org) is used instead of our custom test framework.
// [Codewars' assertion methods](https://github.com/Codewars/codewars.com/wiki/Codewars-JavaScript-Test-Framework)
// are still available for now.
//
// For new tests, using [Chai](https://chaijs.com/) is recommended.
// You can use it by requiring:
//     const assert = require("chai").assert;
// If the failure output for deep equality is truncated, `chai.config.truncateThreshold` can be adjusted.

describe("Solution", function() {
  it("should test for something", function() {
    // Test.assertEquals(1 + 1, 2);
    // assert.strictEqual(1 + 1, 2);
  });
});

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