arr = [1, 1, [1], [[1, 1, [1, 1]]], [1, [1, 1], 1]]

def f(x):
    if isinstance(x,(float,int)):
        return x
    else:
        return sum(f(z) for z in x)

def g(x):
    brr=[x]
    s=0
    while brr:
        if isinstance(u:=brr.pop(),(float,int)):
            s+=u
        else:
            brr.extend(u)
    return s

print(f(arr))
print(g(arr))

from timeit import *
for u in [f,g,g,f,f,g,g,f]:
    print(f'{u.__name__}: {timeit(lambda:u(arr),number=100000)}')