diff --git a/sorts/bubble_sort.py b/sorts/bubble_sort.py
index 359a4b21d..9ff987fa9 100644
--- a/sorts/bubble_sort.py
+++ b/sorts/bubble_sort.py
@@ -1,18 +1,34 @@
 from __future__ import print_function
 
-def bubble_sort(arr):
-  n = len(arr)
-  # Traverse through all array elements
-  for i in range(n):
-    # Last i elements are already in place
-      for j in range(0, n-i-1):
-        # traverse the array from 0 to n-i-1
-        # Swap if the element found is greater
-        # than the next element
-        if arr[j] > arr[j+1] :
-              arr[j], arr[j+1] = arr[j+1], arr[j]
-  return arr
- 
+
+def bubble_sort(collection):
+    """Pure implementation of bubble sort algorithm in Python
+
+    :param collection: some mutable ordered collection with heterogeneous
+    comparable items inside
+    :return: the same collection ordered by ascending
+
+    Examples:
+    >>> bubble_sort([0, 5, 3, 2, 2])
+    [0, 2, 2, 3, 5]
+
+    >>> bubble_sort([])
+    []
+
+    >>> bubble_sort([-2, -5, -45])
+    [-45, -5, -2]
+    """
+    length = len(collection)
+    for i in range(length-1):
+        swapped = False
+        for j in range(length-1-i):
+            if collection[j] > collection[j+1]:
+                swapped = True
+                collection[j], collection[j+1] = collection[j+1], collection[j]
+        if not swapped: break  # Stop iteration if the collection is sorted.
+    return collection
+
+
 if __name__ == '__main__':
     try:
         raw_input          # Python 2
diff --git a/sorts/selection_sort.py b/sorts/selection_sort.py
index 432d14090..c1d66c5a8 100644
--- a/sorts/selection_sort.py
+++ b/sorts/selection_sort.py
@@ -31,7 +31,7 @@ def selection_sort(collection):
     """
 
     length = len(collection)
-    for i in range(length):
+    for i in range(length - 1):
         least = i
         for k in range(i + 1, length):
             if collection[k] < collection[least]: