Strings in Python

[Johny]

Playing a little more with strings, I found out that string.find
function provides the position of
the first occurance of the substring in the string.
Is there a way how to find out all substring's position ?
To explain more,
let's suppose

mystring='12341'
import string

>>> string.find(mystring ,'1')
0

But I need to find the  possition the other '1' in mystring too.
Is it possible?
Or must I use regex?
Thanks for help
L