Update counter.py

data/contexts/counter.py

@@ -3,16 +3,18 @@ import threading
 class Counter:
     def __init__(self):
         self.count = 0
+        self.lock = threading.Lock()
     
     def increment(self):
-        current = self.count
-        self.count = current + 1
-        return self.count
-    
-    def get_count(self):
-        return self.count
+        with self.lock:
+            self.count += 1
+            return self.count
     
     def decrement(self):
-        current = self.count
-        self.count = current - 1
-        return self.count
+        with self.lock:
+            self.count -= 1
+            return self.count
+    
+    def get_count(self):
+        with self.lock:
+            return self.count