So it says that levelUp(p: player) is not a text but I have this isn't it right
code_language.skript:
function levelUp(p: player):
if {xp::_p} >= {xpRequired::_p}:
set {xp::_p} to 0
add 1 to {level::_p}
add 1 to {_p}'s level
set {xpRequired::_p} to ({xpRequired::_p} * 1.15)