Backported to v0.3.1 from:
https://github.com/laike9m/pdir2/commit/5d44803dca3c24eba44aac373a8e06ebacea59a5

diff -Nurp pdir2-0.3.1.orig/pdir/attr_category.py pdir2-0.3.1/pdir/attr_category.py
--- pdir2-0.3.1.orig/pdir/attr_category.py	2020-01-23 16:58:02.899783934 -0600
+++ pdir2-0.3.1/pdir/attr_category.py	2020-01-23 16:58:50.576002074 -0600
@@ -1,4 +1,4 @@
-import collections
+import collections.abc
 import functools
 import inspect
 from enum import IntEnum  # TODO: use native Python 3 enum
@@ -71,14 +71,14 @@ ATTR_MAP = {
     '__next__': (AttrCategory.ITER, AttrCategory.FUNCTION),
     '__reversed__': [
         (
-            lambda obj: isinstance(obj, collections.Iterator),
+            lambda obj: isinstance(obj, collections.abc.Iterator),
             (AttrCategory.ITER, AttrCategory.FUNCTION),
         ),
         (_always_true, (AttrCategory.CONTAINER, AttrCategory.FUNCTION)),
     ],
     '__iter__': [
         (
-            lambda obj: isinstance(obj, collections.Iterator),
+            lambda obj: isinstance(obj, collections.abc.Iterator),
             (AttrCategory.ITER, AttrCategory.FUNCTION),
         ),
         (_always_true, (AttrCategory.CONTAINER, AttrCategory.FUNCTION)),