You don't have to do anything with it, but I always use _x for a throwaway variable.
for example a timer for a weapon shooting.
## timer node
onready var timer: Timer = $"CoolDownTimer"
var _x:int = 0
_x = timer.connect("timeout", self, "_on_timeout")
timer.one_shot = true
timer.wait_time = 0.1
can_shoot = true