def fibonacci(size):
    a, b = 1, 1
    for x in range(size):
        if x in (0, 1): x = 1 
        x = a + b
        a, b = b, x
        yield x

# Called in a "for" loop    
for x in fibonacci(10):
    print(x)

# Assigned to a variable
foo = fibonacci(10)
print(next(foo))
print(next(foo))