fixup! Implement Lambda function versions (#5927)

Author: dsotirho-ucsc

scripts/sell_unused_slots.py

@@ -95,6 +95,9 @@ def _lambda_invocation_counts(self) -> dict[Lambda, int]:
                                 'Namespace': 'AWS/Lambda',
                                 'MetricName': 'Invocations',
                                 'Dimensions': [{
+                                    # The 'FunctionName' dimension returns
+                                    # aggregate metrics for all versions and
+                                    # aliases of the function.
                                     'Name': 'FunctionName',
                                     'Value': lambda_.name
                                 }]

src/azul/lambdas.py

@@ -106,6 +106,8 @@ def _lambda(self):
         return aws.lambda_
 
     def list_lambdas(self) -> list[Lambda]:
+        # Note that this method returns the unpublished "$LATEST" version of
+        # each function.
         return [
             Lambda.from_response(function)
             for response in self._lambda.get_paginator('list_functions').paginate()