>>> from prog import *

>>> it = aritmetica(3, 2)
>>> for i in range(5):
...     print(next(it), end=', ')
3, 5, 7, 9, 11, 

>>> it = geometrica(2, 3)
>>> for i in range(5):
...     print(next(it), end=', ')
2, 6, 18, 54, 162,