import itertools

class c1():
    def getYield():
        for i in range(3):
            yield i

class c2():
    def getYield():
        for i in range(5):
            yield i

class c3():
    def getYield():
        for i in range(7):
            yield i
sc = {}
sc['y1'] = c1
sc['y2'] = c2
sc['y3'] = c3

sc_list = [(k,v) for k,v in sc.items()]

y = []
for p in itertools.product(*[v.getYield() for k,v in sc_list]):
    z = {}
    for i in range(len(p)):
        z[sc_list[i][0]] = p[i]
    y.append(z)
print(y)