There were multiple rounds for this interview. First step was to parse a CSV string. It was essentially a long string (see end of description). I wasn't sure how to parse it as there were no new lines, I asked if I can just add them in. JavaScript is the language I used but was not the best choice. I should have used TypeScript as it would have made it easier to make objects with type safety and keep the code clean and organized. After parsing it you are supposed to calculate the transaction fee which was trivial. Next question was to then add more if/else logic but pertaining to if payment was completed, but country was 'ie', and the item was Klarna or was a 'card' then X was the fee. Idea was NOT to write everything in one method but different methods to keep the code organized. CSV = "id,reference,amount,currency,date,merchant_id,buyer_country,transaction_type,payment_provider,status py_1,1,1000,eur,2025-01-01,acct_1,ie,payment,card,payment_completed py_2,2,2500,eur,2025-01-01,acct_1,de,payment,card,payment_completed"