`os.urandom()` maps to ints in [0, 255]

mapto.py

# Informal proof

from math import inf

mn, mx = inf, -1 * inf

for _ in range(100000):
    b = os.urandom(10)
    new_min = min(b)
    new_max = max(b)
    if new_min < mn:
        mn = new_min
    if new_max > mx:
        mx = new_max

if __name__ == '__main__':
  print(mn, mx)
  # (0, 255)