lista atual=[1, 2], somando 1 com soma_ll([2])
lista atual=[2], somando 2 com soma_ll([])
Traceback (most recent call last):
File "./prog.py", line 5, in <module>
File "./prog.py", line 3, in soma_ll
File "./prog.py", line 3, in soma_ll
File "./prog.py", line 2, in soma_ll
IndexError: list index out of range