some teachers believe that they can help children concentrate – especially those with ADHD.

And some believe that they are distracting to everyone else in the class: https://www.theguardian.com/teacher-network/2017/apr/29/secr...

Also there is no evidence yet that they do help concentration, so it is only anecdotal evidence at this stage.

My brother was prescribed a fidget toy by an educational psychologist about 10 years ago. At that time, even though both of my parents were teachers, they'd never seen them before.

His was a rubbery snake-like thing, which didn't make any noise. It should have been less distracting to the class than clicking a pen, or tapping fingers on the desk.

Now that there are thousands of them on eBay, and they seem to have become a trend, I can well believe they're a distraction in class.

why not use github for package repository?

Do you mean git? Not sure what difference github makes over vanilla git in this case..

GoLang kind of does this (via "go get") and it sucks for multiple reasons:

-you can only distribute packages as source, meaning you need to compile them yourself (this has pros and cons, but it would be nice to be able to distribute binaries if you want)

-your dependencies reference a commit hash, and unless you micromanage your dependencies and constantly look at the github repository's tags, you have no semantic versioning, making it a lot more likely you'll encounter breakages

-there's no way for your dependencies to specify dependencies, unless they're using git submodules (very few projects do), and even with submodules, you can't share dependencies across packages

The list goes on..

Git is for source control. Package managers offer a lot of different (and awesome IMO) features. Lack of package management is one of my biggest gripes with GoLang honestly.

I do if that cryptocurrencies are as easy as concrete currency.

visual is good but is it faster then keyboard coding? I think that just for fun.

same question: I want to able hack/modify/change a car to high performance car. do I need to understand how it work? how does an engine work? what kind of parts I need? I think you should understand how does cpu and memory work. how does network work. how does cryptography work. what kind of tools able hack.

I somehow did not get what you intended to convey. Can you please elaborate? Would going back to Algos and OS etc. help me grow as a hard core programmer?

I used Linux/Apache/PHP/MySQL over 16 years and while changed 5 jobs. I am still learning new programming languages(swift) or some programming languages I have not learnt yet like embedded C. that is true if you can master one programming language then you can easier to pickup difference programming languages.

Thanks for C language and Pascal that basic concept i learnt from high school.

You should learn C++ and Javascript;

I'd recommend PHP instead of JS of you want to learn the truly worst language and ecosystem in the world. JS is just second place.

China, Welcome you. :-)