diff --git a/src/4/creating_data_processing_pipelines/example.py b/src/4/creating_data_processing_pipelines/example.py
index a7ff39a..9a2de51 100644
--- a/src/4/creating_data_processing_pipelines/example.py
+++ b/src/4/creating_data_processing_pipelines/example.py
@@ -10,7 +10,7 @@ def gen_find(filepat, top):
     '''
     for path, dirlist, filelist in os.walk(top):
         for name in fnmatch.filter(filelist, filepat):
-            yield os.path.join(path,name)
+            yield os.path.join(path, name)
 
 def gen_opener(filenames):
     '''
diff --git a/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example1.py b/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example1.py
index 85f6517..85e1ae6 100644
--- a/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example1.py
+++ b/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example1.py
@@ -1,5 +1,7 @@
 # Example of using partial() with sorting a list of (x,y) coordinates
 
+import functools
+
 points = [ (1, 2), (3, 4), (5, 6), (7, 7) ]
 
 import math
@@ -9,5 +11,5 @@ def distance(p1, p2):
     return math.hypot(x2 - x1, y2 - y1)
 
 pt = (4,3)
-points.sort(key=partial(distance, pt))
+points.sort(key=functools.partial(distance, pt))
 print(points)
diff --git a/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example2.py b/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example2.py
index bfe4f0e..4071f2e 100644
--- a/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example2.py
+++ b/src/7/making_an_n-argument_callable_work_as_a_callable_with_fewer_arguments/example2.py
@@ -1,5 +1,7 @@
 # Using partial to supply extra arguments to a callback function
 
+import functools
+
 def output_result(result, log=None):
     if log is not None:
         log.debug('Got: %r', result)
@@ -17,6 +19,6 @@ def add(x, y):
     log = logging.getLogger('test')
 
     p = Pool()
-    p.apply_async(add, (3, 4), callback=partial(output_result, log=log))
+    p.apply_async(add, (3, 4), callback=functools.partial(output_result, log=log))
     p.close()
     p.join()
diff --git a/src/8/implementing_custom_containers/example1.py b/src/8/implementing_custom_containers/example1.py
index f8ab10f..a5d6112 100644
--- a/src/8/implementing_custom_containers/example1.py
+++ b/src/8/implementing_custom_containers/example1.py
@@ -5,7 +5,7 @@
 
 class SortedItems(collections.Sequence):
     def __init__(self, initial=None):
-        self._items = sorted(initial) if initial is None else []
+        self._items = sorted(initial) if initial is not None else []
 
     # Required sequence methods
     def __getitem__(self, index):
diff --git a/src/8/implementing_custom_containers/example2.py b/src/8/implementing_custom_containers/example2.py
index f9cc6a5..cf2fd29 100644
--- a/src/8/implementing_custom_containers/example2.py
+++ b/src/8/implementing_custom_containers/example2.py
@@ -2,7 +2,7 @@
 
 class Items(collections.MutableSequence):
     def __init__(self, initial=None):
-        self._items = list(initial) if initial is None else []
+        self._items = list(initial) if initial is not None else []
 
     # Required sequence methods
     def __getitem__(self, index):