chore: add Counter class

src/counter.py

@@ -0,0 +1,20 @@
+
+class Counter:
+  def __init__(self, val=0):
+    self.reset_on = val
+    self.val = val
+  
+  def __repr__(self):
+    return f"Counter: {self.val} [reset on {self.reset_on}]"
+  
+  def incr(self):
+    self.val += 1
+    return self.val
+
+  def decr(self):
+    self.val -= 1
+    return self.val
+
+  def reset(self):
+    self.val = self.reset_on
+    return self.val