Merge sort in python

merge.py

def     __merge(a, lo, hi):
       """__merge(a,lo,hi) merge sorts array a from
       index lo to index hi, where 0<=lo <= hi < len(a)."""
       if lo < hi:
               m = (lo+hi)/2
               __merge(a,lo,m)
               __merge(a,m+1,hi)
               b = a[lo:m+1]
               c = a[m+1:hi+1]
               i = j = 0;
               for k in range(lo,hi+1):
                       if i < len(b) and (j == len(c) or b[i] < c[j]):
                               a[k] = b[i]
                               i +=1
                       else:
                               a[k] = c[j]
                               j +=1



def     mergesort(a):
       __merge(a, 0, len(a)-1)



if __name__ == '__main__':
       from random import shuffle
       a = range(120)
       for i in range(10):
               print 'trial ', i+1
               shuffle(a)
               print(a)
               mergesort(a)
               print(a)