Counting all permutations of a substring

[Azolex]

[counting all (possibly overlapping) occurences of a substring in a string]

def count_subs(s,subs,pos=0) :
     pos = 1+s.find(subs,pos)
     return pos and 1+count_subs(s,subs,pos)

or equivalently

def count_subs(s,subs)
     pos,cnt = 0,0
     while True :
         pos = 1+s.find(subs,pos)
         if not pos :
             return cnt
         cnt += 1

or even (using the helper functions of my last post in the "small 
challenge" thread)

def count_subs(s,subs) :
     cnt = 0
     for pos1 in echoback(1+s.find(subs,pos) for pos in itially(0)) :
         if not pos1 :
             return cnt
         cnt += 1


(I've minimally tested only the first version)