For the life of me I cannot figure out how to do this thing.
>>> Exchange Emerald for "Currency"

How hard can this be? Stupid. There's a thousand tutorials on Creating Currency, exchanging currency with currency, and exchanging Currency for Item, but Not Item for currency! THE FLIP MAN!!!

A. Read the Amount of Emerald in inventory as 1 or more
B. Take out 1 Emerald from inventory
C. Give Player 1 Currency