Adds Counter class; prints 1–10.

counter.py

@@ -0,0 +1,25 @@
+class Counter:
+    def __init__(self, start: int = 0) -> None:
+        self._value = start
+
+    def increment(self, amount: int = 1) -> int:
+        self._value += amount
+        return self._value
+
+    def decrement(self, amount: int = 1) -> int:
+        self._value -= amount
+        return self._value
+
+    def get_value(self) -> int:
+        return self._value
+
+
+def main() -> None:
+    c = Counter(0)
+    for _ in range(10):
+        c.increment()
+        print(c.get_value())
+
+
+if __name__ == "__main__":
+    main()