import itertools

def coeficients_polinomi1(p):
    i = 0
    while True:
        if i in p:
            yield i, p[i]
        else:
            yield i, 0
        i = i + 1

def coeficients_polinomi2(p):
    return map(lambda i: (i, p.get(i, 0)), itertools.count())

def coeficients_polinomi3(p):
    return ((g, p.get(g, 0)) for g in itertools.count(0))


# tria la solució que vols provar
coeficients_polinomi = coeficients_polinomi1