sum of nested list in Python

Question

I try to sum a list of nested elements

e.g, numbers=[1,3,5,6,[7,8]] should produce sum=30

I wrote the following code :

Answer 1

This code also works.

def add_all(t):
    total = 0
    for i in t:
        if type(i) == list: # check whether i is list or not
            total = total + add_all(i)
        else:
            total += i
    return total