def mutate_string(string, position, character):

q = list(string)
q[position] = f'{character}'
length = len(q)
ss = ""
x=0
def concatinate():
    nonlocal q
    nonlocal x
    nonlocal ss 
    if x < length :
        ss+= str(q[x]) 
        x+=1 
        return concatinate()
concatinate()    
print(ss)

mutate_string("eerwewewe232xz",8,"%@#!")