fibonacci infinitesimally

a = 0
b = 1
while a < 200:
    a # we state a before the math is done so the sequence starts at 0 and not 1
    a, b + b, a + b
    if  a > 0:
        print("a is not infinitesimally, forever approaching an output (ref line 12)")
    else:
        if a == 0:
            print("a is infinitesimally,.is this division by zero? line 5 goes into line 12 x number of times")
    if a > 21:
        print(a)
        a, b = b + a, b + b
# the computer is lying. why doesn't it count over 21?
# trying to reach line 12 without setting a variable on lines 4-5