python fibonacci number generator code in less than 40 bytes

fibonacci.py

f=lambda a,b,n:f(b,a+b,n-1)if n>1else b # simple and fast

# for test
import sys
sys.setrecursionlimit(5001) # as default, it was 1000 in my computer
print(f(0,1,5000)) # 0 1 1 2 3 5 8 13 21 ...
print(f(1,1,5000)) # 1 1 2 3 5 8 13 21 34 ...