GooPUnlockable{}
Unlockables are persistent (remembered across server reboots) variables, more information in their manual page.
Just another way of accomplishing a lot of things that can be accomplished in a lot of other ways.
The "value" you choose has very specific meanings:
Choose "FALSE" to require the unlockable to be in locked state, same thing as choosing value=0
Choose "TRUE" to require the unlockable to be unlocked, any value of the unlockable will suffice
Specify a range for the Unlockable to succeed, for example 3..8. Unlockables are only locked when their value is 0.
Consider visiting the page on unlockables for better understanding.
The ability will only continue after the command /goop unlockables unlock %player% SandwichPerk true has been ran for this player.
Having unlocked the unlockable is not enough, must have unlocked it with the specific value