This kata uses Node.js v8, which doesn't support flat method. flat method is added on Node.js in version 11.15.0

still a virgin, huh?

Im sorry, but this is way over my head, I cannot understand how this explains why prod fails

Hey there. It appears you're new here, so here's some tips:

• When posting code, DO mark it as 'having spoiler content', otherwise everyone on front-page can see your solution, which spoils the fun. (I already marked this one for you)
• When posting code for help, format it correctly (click this link, section: Block Code Formatting), otherwise it's hard to read and copying it requires us to manually indent everything, which isn't ideal...
• Sample tests are just there to show you what's expected. When you hit 'attempt', there's at least 100 random tests generated to test the perfomance (notice perfomance tag in description). This means your code is too slow for this task :/ (too high time complexity). It could be due to excessive sorting or reversing, I'm not sure. (I haven't checked, maybe someone else can help you there)

Happy coding!

Just read the docs...

The type of the returned array, as well as of the accumulator in which the elements are multiplied. The dtype of a is used by default unless a has an integer dtype of less precision than the default platform integer. In that case, if a is signed then the platform integer is used while if a is unsigned then an unsigned integer of the same precision as the platform integer is used.