Implement operation counting for special loopy functions by delegating

Using the same concept we use for visiting with hasattr.

python/dune/codegen/sumfact/vectorization.py

@@ -144,6 +144,12 @@ class PrimitiveApproximateOpcounter(FlopCounter):
     def map_tagged_variable(self, expr):
         return self.map_variable(expr)
 
+    def map_loopy_function_identifier(self, expr):
+        if hasattr(expr, "operations"):
+            return expr.operations()
+
+        raise NotImplementedError("The class {} should implement a symbolic flopcounter.".format(type(expr)))
+
 
 @kernel_cached
 def store_operation_count(expr, count):