diff --git a/11-pythonic-obj/vector2d_v3.py b/11-pythonic-obj/vector2d_v3.py
index 5812dcf..6f5e465 100644
--- a/11-pythonic-obj/vector2d_v3.py
+++ b/11-pythonic-obj/vector2d_v3.py
@@ -79,8 +79,8 @@ Tests of hashing:
 
     >>> v1 = Vector2d(3, 4)
     >>> v2 = Vector2d(3.1, 4.2)
-    >>> hash(v1), hash(v2)
-    (7, 384307168202284039)
+    >>> hash(v1) != hash(v2)
+    True
     >>> len(set([v1, v2]))
     2
 
@@ -122,7 +122,7 @@ class Vector2d:
         return tuple(self) == tuple(other)
 
     def __hash__(self):
-        return hash(self.x) ^ hash(self.y)
+        return hash((self.x, self.y))
 
     def __abs__(self):
         return math.hypot(self.x, self.y)
diff --git a/11-pythonic-obj/vector2d_v3_prophash.py b/11-pythonic-obj/vector2d_v3_prophash.py
index 2eca4ec..37a8e4a 100644
--- a/11-pythonic-obj/vector2d_v3_prophash.py
+++ b/11-pythonic-obj/vector2d_v3_prophash.py
@@ -81,8 +81,8 @@ Tests of hashing:
 
     >>> v1 = Vector2d(3, 4)
     >>> v2 = Vector2d(3.1, 4.2)
-    >>> hash(v1), hash(v2)
-    (7, 384307168202284039)
+    >>> hash(v1) != hash(v2)
+    True
     >>> len(set([v1, v2]))
     2
 
@@ -131,7 +131,7 @@ class Vector2d:
 
 # BEGIN VECTOR_V3_HASH
     def __hash__(self):
-        return hash(self.x) ^ hash(self.y)
+        return hash((self.x, self.y))
 # END VECTOR_V3_HASH
 
     def __abs__(self):
diff --git a/11-pythonic-obj/vector2d_v3_slots.py b/11-pythonic-obj/vector2d_v3_slots.py
index a9d700d..cc091b0 100644
--- a/11-pythonic-obj/vector2d_v3_slots.py
+++ b/11-pythonic-obj/vector2d_v3_slots.py
@@ -78,8 +78,8 @@ Tests of hashing:
 
     >>> v1 = Vector2d(3, 4)
     >>> v2 = Vector2d(3.1, 4.2)
-    >>> hash(v1), hash(v2)
-    (7, 384307168202284039)
+    >>> hash(v1) != hash(v2)
+    True
     >>> len(set([v1, v2]))
     2
 
@@ -129,7 +129,7 @@ class Vector2d:
         return tuple(self) == tuple(other)
 
     def __hash__(self):
-        return hash(self.x) ^ hash(self.y)
+        return hash((self.x, self.y))
 
     def __abs__(self):
         return math.hypot(self.x, self.y)
diff --git a/16-op-overloading/vector2d_v3.py b/16-op-overloading/vector2d_v3.py
deleted file mode 100644
index 5812dcf..0000000
--- a/16-op-overloading/vector2d_v3.py
+++ /dev/null
@@ -1,151 +0,0 @@
-"""
-A 2-dimensional vector class
-
-    >>> v1 = Vector2d(3, 4)
-    >>> print(v1.x, v1.y)
-    3.0 4.0
-    >>> x, y = v1
-    >>> x, y
-    (3.0, 4.0)
-    >>> v1
-    Vector2d(3.0, 4.0)
-    >>> v1_clone = eval(repr(v1))
-    >>> v1 == v1_clone
-    True
-    >>> print(v1)
-    (3.0, 4.0)
-    >>> octets = bytes(v1)
-    >>> octets
-    b'd\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'
-    >>> abs(v1)
-    5.0
-    >>> bool(v1), bool(Vector2d(0, 0))
-    (True, False)
-
-
-Test of ``.frombytes()`` class method:
-
-    >>> v1_clone = Vector2d.frombytes(bytes(v1))
-    >>> v1_clone
-    Vector2d(3.0, 4.0)
-    >>> v1 == v1_clone
-    True
-
-
-Tests of ``format()`` with Cartesian coordinates:
-
-    >>> format(v1)
-    '(3.0, 4.0)'
-    >>> format(v1, '.2f')
-    '(3.00, 4.00)'
-    >>> format(v1, '.3e')
-    '(3.000e+00, 4.000e+00)'
-
-
-Tests of the ``angle`` method::
-
-    >>> Vector2d(0, 0).angle()
-    0.0
-    >>> Vector2d(1, 0).angle()
-    0.0
-    >>> epsilon = 10**-8
-    >>> abs(Vector2d(0, 1).angle() - math.pi/2) < epsilon
-    True
-    >>> abs(Vector2d(1, 1).angle() - math.pi/4) < epsilon
-    True
-
-
-Tests of ``format()`` with polar coordinates:
-
-    >>> format(Vector2d(1, 1), 'p')  # doctest:+ELLIPSIS
-    '<1.414213..., 0.785398...>'
-    >>> format(Vector2d(1, 1), '.3ep')
-    '<1.414e+00, 7.854e-01>'
-    >>> format(Vector2d(1, 1), '0.5fp')
-    '<1.41421, 0.78540>'
-
-
-Tests of `x` and `y` read-only properties:
-
-    >>> v1.x, v1.y
-    (3.0, 4.0)
-    >>> v1.x = 123
-    Traceback (most recent call last):
-      ...
-    AttributeError: can't set attribute
-
-
-Tests of hashing:
-
-    >>> v1 = Vector2d(3, 4)
-    >>> v2 = Vector2d(3.1, 4.2)
-    >>> hash(v1), hash(v2)
-    (7, 384307168202284039)
-    >>> len(set([v1, v2]))
-    2
-
-"""
-
-from array import array
-import math
-
-class Vector2d:
-    typecode = 'd'
-
-    def __init__(self, x, y):
-        self.__x = float(x)
-        self.__y = float(y)
-
-    @property
-    def x(self):
-        return self.__x
-
-    @property
-    def y(self):
-        return self.__y
-
-    def __iter__(self):
-        return (i for i in (self.x, self.y))
-
-    def __repr__(self):
-        class_name = type(self).__name__
-        return '{}({!r}, {!r})'.format(class_name, *self)
-
-    def __str__(self):
-        return str(tuple(self))
-
-    def __bytes__(self):
-        return (bytes([ord(self.typecode)]) +
-                bytes(array(self.typecode, self)))
-
-    def __eq__(self, other):
-        return tuple(self) == tuple(other)
-
-    def __hash__(self):
-        return hash(self.x) ^ hash(self.y)
-
-    def __abs__(self):
-        return math.hypot(self.x, self.y)
-
-    def __bool__(self):
-        return bool(abs(self))
-
-    def angle(self):
-        return math.atan2(self.y, self.x)
-
-    def __format__(self, fmt_spec=''):
-        if fmt_spec.endswith('p'):
-            fmt_spec = fmt_spec[:-1]
-            coords = (abs(self), self.angle())
-            outer_fmt = '<{}, {}>'
-        else:
-            coords = self
-            outer_fmt = '({}, {})'
-        components = (format(c, fmt_spec) for c in coords)
-        return outer_fmt.format(*components)
-
-    @classmethod
-    def frombytes(cls, octets):
-        typecode = chr(octets[0])
-        memv = memoryview(octets[1:]).cast(typecode)
-        return cls(*memv)