def fibonacci():
i1, i2 = 0, 1
while 1:
yield i1
i1,i2 = i2,i1+i2
fibo = fibonacci()
first10fibo = [fibo.next() for x in range(10)]
next10fibo = [fibo.next() for x in range(10)]use in a loop
fibo = fibonacci()
for x in fibo:
if x > 1000: break
print x