Added sleep-sort

sorts/sleepsort.py

@@ -1,23 +1,32 @@
-"""
-Sleepsort is probably the wierdest of all sorting functions
+"""Sleepsort is probably the wierdest of all sorting functions
 with time-complexity of O(max(input)+n) which is
 quite different from almost all other sorting techniques.
 If the number of inputs is small then the complexity
 can be approximated to be O(max(input)) which is a constant
 
-If the number of inputs is large then the complexity is
-approximately O(n)
+If the number of inputs is large, the complexity is
+approximately O(n).
 
 This function uses multithreading a kind of higher order programming
 and calls n functions, each with a sleep time equal to its number.
-Hence each of the functions wake in Sorted form
+Hence each of the functions wake in sorted form.
 
-But this function is not stable for very large values
+This function is not stable for very large values.
 """
+
 from time import sleep
 from threading import Timer
-
-def sleepsort(values):
+from typing import List
+
+
+def sleepsort(values: List[int]) -> List[int]:
+    """
+    Sort the list using sleepsort.
+    >>> sleepsort([3, 2, 4, 7, 3, 6, 9, 1])
+    [1, 2, 3, 3, 4, 6, 7, 9]
+    >>> sleepsort([3, 2, 1, 9, 8, 4, 2])
+    [1, 2, 2, 3, 4, 8, 9]
+    """
     sleepsort.result = []
     def add1(x):
         sleepsort.result.append(x)
@@ -30,6 +39,8 @@ def add1(x):
     return sleepsort.result
 
 if __name__ == '__main__':
+    import doctest
+    doctest.testmod
     x = [3,2,4,7,3,6,9,1]
     sorted_x=sleepsort(x)
     print(sorted_x)