Same for the abstract superclasses.

src/awkward/types/arraytype.py

@@ -8,7 +8,7 @@
 
 class ArrayType:
     def __init__(self, content, length):
-        if not isinstance(content, awkward.types.type.Type):
+        if not isinstance(content, ak.types.Type):
             raise ak._errors.wrap_error(
                 TypeError(
                     "{} all 'contents' must be Type subclasses, not {}".format(