Walk me through performing a proof of cash and what it actually proves.

A proof of cash reconciles reported revenue and key P&L items to actual cash movements through the bank, over a period. Mechanically: start from opening bank balances, add recorded receipts and deduct recorded payments per the books, and reconcile to closing bank statements, investigating differences (timing, non-cash items, intercompany, unrecorded transactions). What it proves: that the reported numbers are backed by real cash flowing through the bank, not just ledger entries — it's a powerful anti-fraud and earnings-quality test because fictitious revenue rarely produces matching cash. It surfaces revenue recorded with no corresponding collection, round-tripping, unusual intercompany funding plugging gaps, and cut-off issues at period ends. It's especially valuable where you doubt the MI's reliability or the audited data is thin, because cash is hard to fake at scale.