def mutate_string(string, position, character): string = string[:int(position)] + str(character) + string[int(position)+1:] return string

li = list(string)
li[position] = character
return "".join(li)

I think this code work perfectly

def mutate_string(string, position, character): lst = list(string) lst[position] = character string1 = ' '.join(lst) return string1

if name == 'main': s = input() i, c = input().split() s_new = mutate_string(s, int(i), c) print(s_new)

def mutate_string(string, position, character): C=list(s) C[position] = character

    return ''.join(C)

Another Solution

def mutate_string(s, i, c):
        s_list = list(s)
        s_list[i] = c
        return "".join(s_list)