Merge sort implementation

merge_sort.py

# Python version 2.6+

from heapq import merge
 
def merge_sort(m):
    if len(m) <= 1:
        return m
 
    middle = len(m) / 2
    left = m[:middle]
    right = m[middle:]
 
    left = merge_sort(left)
    right = merge_sort(right)
    return list(merge(left, right))