Making nested lists in python : This was the question " Write a function *find_all(L, i)* that takes a nested list *L* and, an item *i* and, prints the indices of all occurrences of *i* in *L*.

I wrote this code 
from string import *
def *find_all(L,i)*:
    for *sub_list* in *L*:
        if *i* in *sub_list*:
            return *(L.index(sub_list), sub_list.index(i))*
print *find_all([[1,2,3],[4,5],[6],[5,13]], 5)*


It only prints (1,1).  
