Refactors decorator counter methodology

Now it's a decorator on the __call__ function.

That way we decouple the logic for telemetry needs -- without
it explicitly living within the NodeTransformLifecycle class.
I mean it's still coupled, it's just we can now change
that functionality more clearly.

hamilton/function_modifiers/base.py

@@ -1,5 +1,6 @@
 import abc
 import collections
+import functools
 from typing import Any, Callable, Collection, Dict, List, Tuple
 
 from hamilton import node
@@ -22,6 +23,26 @@ def sanitize_function_name(name: str) -> str:
 COUNTER = collections.defaultdict(int)
 
 
+def track_decorator_usage(call_fn: Callable) -> Callable:
+    """Decorator to wrap the __call__ to count decorator usage.
+
+    :param call_fn: the `__call__` function.
+    :return: the wrapped call function.
+    """
+
+    @functools.wraps(call_fn)
+    def replace__call__(self, fn):
+        global COUNTER
+        if self.__module__.startswith("hamilton.function_modifiers"):
+            # only capture counts for hamilton decorators
+            COUNTER[self.__class__.__name__] = COUNTER[self.__class__.__name__] + 1
+        else:
+            COUNTER["custom_decorator"] = COUNTER["custom_decorator"] + 1
+        return call_fn(self, fn)
+
+    return replace__call__
+
+
 class NodeTransformLifecycle(abc.ABC):
     """Base class to represent the decorator lifecycle. Common among all node decorators."""
 
@@ -51,14 +72,7 @@ def validate(self, fn: Callable):
         """
         pass
 
-    def count_decorator_usage(self):
-        global COUNTER
-        if self.__module__.startswith("hamilton.function_modifiers"):
-            # only capture counts for hamilton decorators
-            COUNTER[self.__class__.__name__] = COUNTER[self.__class__.__name__] + 1
-        else:
-            COUNTER["custom_decorator"] = COUNTER["custom_decorator"] + 1
-
+    @track_decorator_usage
     def __call__(self, fn: Callable):
         """Calls the decorator by adding attributes using the get_lifecycle_name string.
         These attributes are the pointer to the decorator object itself, and used later in resolve_nodes below.
@@ -67,7 +81,6 @@ def __call__(self, fn: Callable):
         :return: The function again, with the desired properties.
         """
         self.validate(fn)
-        self.count_decorator_usage()
         lifecycle_name = self.__class__.get_lifecycle_name()
         if hasattr(fn, self.get_lifecycle_name()):
             if not self.allows_multiple():