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# AI solution for JavaScript Coding Question on BFE.dev

23. create a sum()

One possible solution using closures is:

`function sum(num1) { return function(num2) { if (num2) { return sum(num1 + num2); } else { return num1; } };}`

This function returns a new function each time it's called, that either adds a new number to the sum or returns the current sum if no argument is provided. The function keeps track of the current sum using closures.