Implement _check

[Yzquile]

Centralized input validation into _check() and refactored all calculator operations to remove duplicated logic.

[dantharejabot]

Yay, a pull request!

After you submit a pull request, one of the following will happen:

😭 You don’t get a response. 😭

Even on an active project, it’s possible that your pull request won’t get an immediate response. You should expect some delay as most open source maintainers do so in their free time and can be busy with other tasks.

If you haven’t gotten a response in over a week, it’s fair to politely respond in the same thread, asking someone for a review. If you know the handle of the right person to review your pull request, you can @-mention them to send them a notification. Avoid reaching out to that person privately; remember that public communication is vital to open source projects.

If you make a polite bump and still nobody responds, it’s possible that nobody will respond, ever. It’s not a great feeling, but don’t let that discourage you. It’s happened to everyone! There are many possible reasons why you didn’t get a response, including personal circumstances that may be out of your control. Try to find another project or way to contribute. If anything, this is a good reason not to invest too much time in making a pull request before other community members are engaged and responsive.

🚧 You're asked to make changes to your pull request. 🚧

It’s very common that someone will request changes on your pull request, whether that’s feedback on the scope of your idea, or changes to your code. Often a pull request is just the start of the conversation.

When someone requests changes, be responsive. They’ve taken the time to review your pull request. Opening a PR and walking away is bad form. If you don’t know how to make changes, research the problem, then ask for help if you need it.

If you don’t have time to work on the issue anymore (for example, if the conversation has been going on for months, and your circumstances have changed), let the maintainer know so they’re not expecting a response. Someone else may be happy to take over.

👎 Your pull request doesn’t get accepted. 👎

It's possible your pull request may or may not be accepted in the end. If you’re not sure why it wasn’t accepted, it’s perfectly reasonable to ask the maintainer for feedback and clarification. Ultimately, however, you’ll need to respect that this is their decision. Don’t argue or get hostile. You’re always welcome to fork and work on your own version if you disagree!

🎉 Your pull request gets accepted and merged. 🎉

Hooray! You’ve successfully made an open source contribution!

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Thank you for the submission, @Yzquile! I'll review your code shortly, hang tight.

[dantharejabot]

This is a great attempt, @Yzquile!

I would like to request a few changes before merging your work. Please review my comments below and make the appropriate changes to your code.

After you update your code locally, follow the instructions to save your changes locally and push your changes to your fork.

When you push your changes to your fork, I'll come back for another review.

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There are 3 style guide violations in your contribution. I've marked them with inline comments for your convenience.

Please revisit your code and follow the style guide best practices.

Hint: You might be able to fix some issues automatically by running npm run lint -- --fix

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All the tests are passing. Nice job!

[dantharejabot]

Expected indentation of 2 spaces but found 1.
_{(learn more)}

[dantharejabot]

Expected indentation of 2 spaces but found 1.
_{(learn more)}

[dantharejabot]

Expected indentation of 2 spaces but found 0.
_{(learn more)}