How can I build a counter in python?

Question

I want to have it so that each time I hit the space bar, the number in the terminal increases by one, so that I can keep a number in my head and not forget it. However, if I use

Answer 1

import os

while True:
    cmd = "read -n 1 c; print $c"
    key = os.popen(cmd).read()
    if key[0] == "z":
        x=x+1
        print x