Design a cash register drawer function checkCashRegister() that accepts purchase price as the first argument (price), payment as the second argument (cash), and cash-in-drawer (cid) as the third argument.

Convert the given number into a roman numeral.

Given the array arr, iterate through and remove each element starting from the first element (the 0 index) until the function func returns true when the iterated element is passed through it. Then return the rest of the array once the condition is satisfied, otherwise, arr should be returned as an empty array

Flatten a nested array. You must account for varying levels of nesting.