Why does Itertool Permutations recurse till recursionError in def function?

Question

I'm just wondering why I'm getting the error: RecursionError: maximum recursion depth exceeded When trying:

def permutations(string):
    permlist = permutations(string)
    combolist = []


    for perm in list(permlist): 
        if ''.join(perm) not in combolist:
            combolist.append(''.join(perm))

    print(f"{combolist}")

I get this error:

permlist = permutations(string)
  [Previous line repeated 996 more times]
RecursionError: maximum recursion depth exceeded  

However, when I try it outside of a def, it works no problem:

 
permlist = permutations('abba')
combolist = []
 
 
for perm in list(permlist): 
    if ''.join(perm) not in combolist:
        combolist.append(''.join(perm))
 
print(f"{combolist}")
 

output:

['abba', 'abab', 'aabb', 'baba', 'baab', 'bbaa']

I'm not very familiar with itertools or permutations or anything, but I'm just wondering why the permutation is recurring in a def, is there any way to possibly run the permutation once in the def, when executing the for loop afterwards or something?

Any help would be much appreciated!