why it gives error when adding max argument to sub function

Question

import re

str = "My name is David. Hi David."
pattern = r"David"
# max argument causes error,why???
newstr = re.sub(pattern, "Amy", str,max=0)
print(newstr)

Answer 1

where is max declaration and which is the error?

Answer 2

did you try declaring it outside?

Answer 3

in the newstr var
when i delete it the code works fine
but the code above gives error why