What's wrong with mutating the argument??

I agree with the first bit ;)

That sorted it!

I've never had to use that argument before. Worthy is further investigation!

Thanks.

I am able to pass all except one test.

I receive the following error message:

         TypeError: Reduce of empty array with no initial value
         at Array.reduce
          at solution
          at test
              at /runner/frameworks/javascript/cw-2.js:159:11
          at Promise._execute
          at Promise._resolveFromExecutor
          at new Promise
          at Object.describe
                  at Object.handleError
              at ContextifyScript.Script.runInThisContext
          at Object.exports.runInThisContext
          at Object.

I have tried an if statement to return 0 in the event on an empty array before reducing but still get the same...

Any help appreciated.

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