Create Counter behaviour

Look, I can count!
1, 2, 4, 3, 5...

behaviours/counter.gd

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+extends Node
+class_name Counter
+
+
+signal changed(old: int, new: int)
+
+
+@export var starting_value: int
+
+var value: int
+
+
+func _ready():
+	value = starting_value
+
+func change(amount: int):
+	var old = value
+	value = amount
+	changed.emit(old, value)
+
+func increase(amount: int = 1):
+	if amount < 0:
+		Log.w(self, "Increasing a counter by a negative value.")
+	change(value + amount)
+
+func decrease(amount: int = 1):
+	if amount < 0:
+		Log.w(self, "Decreasing a counter by a negative value.")
+	change(value - amount)

behaviours/counter.tscn

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+[gd_scene load_steps=2 format=3 uid="uid://brvbtvt4em32"]
+
+[sub_resource type="GDScript" id="GDScript_tks6b"]
+script/source = "extends Node
+
+
+# Called when the node enters the scene tree for the first time.
+func _ready() -> void:
+	pass # Replace with function body.
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(delta: float) -> void:
+	pass
+"
+
+[node name="Counter" type="Node"]
+script = SubResource("GDScript_tks6b")