Python append variable to ever occurrence of a substring

Using the function from Stackoverflow,

‘s’ is the original string, ‘sub’ the substring to be replaced, ‘repl’ the string to replace it with and ‘nth’ the nth occurence of the substring in the string ‘s’.

def nth_repl(s, sub, repl, nth):
find = s.find(sub)
i=find != -1
while find != -1 and i != nth:
find = s.find(sub, find+1)
i+=1
if i == nth:
return s[:find]+repl+s[find+len(sub):]
return s

Count occurences of the substring,

num = str.count("text")

Placing this function in a loop which will iterate through every occurrence of the substring in the string and append the index of each nth occurrence with that index.

for i in range(0,num+1):
newstr = nth_repl(str, "text", "text%d"%(i-1), i)
str = newstr

And then,

print str