diff -r 8dea55fb20e9 Lib/_collections_abc.py
--- a/Lib/_collections_abc.py	Sat Aug 23 18:29:02 2014 -0400
+++ b/Lib/_collections_abc.py	Mon Aug 25 00:01:48 2014 +0200
@@ -6,7 +6,7 @@
 Unit tests are in test_collections.
 """
 
-from abc import ABCMeta, abstractmethod
+from abc import ABCMeta, abstractmethod, mrohasattr, mrogetattr
 import sys
 
 __all__ = ["Hashable", "Iterable", "Iterator",
@@ -64,13 +64,9 @@
 
     @classmethod
     def __subclasshook__(cls, C):
-        if cls is Hashable:
-            for B in C.__mro__:
-                if "__hash__" in B.__dict__:
-                    if B.__dict__["__hash__"]:
-                        return True
-                    break
-        return NotImplemented
+        return cls is Hashable \
+            and bool(mrogetattr(C, "__hash__")) \
+            or NotImplemented
 
 
 class Iterable(metaclass=ABCMeta):
@@ -84,10 +80,9 @@
 
     @classmethod
     def __subclasshook__(cls, C):
-        if cls is Iterable:
-            if any("__iter__" in B.__dict__ for B in C.__mro__):
-                return True
-        return NotImplemented
+        return cls is Iterable \
+            and mrohasattr(C, "__iter__") \
+            or NotImplemented
 
 
 class Iterator(Iterable):
@@ -104,11 +99,9 @@
 
     @classmethod
     def __subclasshook__(cls, C):
-        if cls is Iterator:
-            if (any("__next__" in B.__dict__ for B in C.__mro__) and
-                any("__iter__" in B.__dict__ for B in C.__mro__)):
-                return True
-        return NotImplemented
+        return cls is Iterator \
+            and (mrohasattr(C, "__next__") and mrohasattr(C, "__iter__")) \
+            or NotImplemented
 
 Iterator.register(bytes_iterator)
 Iterator.register(bytearray_iterator)
@@ -134,10 +127,9 @@
 
     @classmethod
     def __subclasshook__(cls, C):
-        if cls is Sized:
-            if any("__len__" in B.__dict__ for B in C.__mro__):
-                return True
-        return NotImplemented
+        return cls is Sized \
+            and mrohasattr(C, "__len__") \
+            or NotImplemented
 
 
 class Container(metaclass=ABCMeta):
@@ -150,10 +142,9 @@
 
     @classmethod
     def __subclasshook__(cls, C):
-        if cls is Container:
-            if any("__contains__" in B.__dict__ for B in C.__mro__):
-                return True
-        return NotImplemented
+        return cls is Container \
+            and mrohasattr(C, "__contains__") \
+            or NotImplemented
 
 
 class Callable(metaclass=ABCMeta):
@@ -166,10 +157,9 @@
 
     @classmethod
     def __subclasshook__(cls, C):
-        if cls is Callable:
-            if any("__call__" in B.__dict__ for B in C.__mro__):
-                return True
-        return NotImplemented
+        return cls is Callable \
+            and mrohasattr(C, "__call__") \
+            or NotImplemented
 
 
 ### SETS ###
diff -r 8dea55fb20e9 Lib/abc.py
--- a/Lib/abc.py	Sat Aug 23 18:29:02 2014 -0400
+++ b/Lib/abc.py	Mon Aug 25 00:01:48 2014 +0200
@@ -6,6 +6,17 @@
 from _weakrefset import WeakSet
 
 
+def mrohasattr(cls, attr):
+    "Return wether cls has attr in mro"
+    return any(attr in B.__dict__ for B in cls.__mro__)
+
+def mrogetattr(cls, attr, default=NotImplemented):
+    "Return the first attr of cls found in mro or default (NotImplemented if default not given)"
+    try:
+        return next(B.__dict__[attr] for B in cls.__mro__ if attr in B.__dict__)
+    except StopIteration:
+        return default
+
 def abstractmethod(funcobj):
     """A decorator indicating abstract methods.