This script demonstrate the `flush` argument of print() function.

printflush.py

#!/usr/bin/env python
#-*- coding: utf-8 -*-

from __future__ import print_function
from time import sleep

string = "The words in this sentence should appear letter by letter."

print("Please wait if you don't see another sentence appearing below.", end="\n\n")

for characters in string:
    # If flush disabled the another line will appear at once and not char by char.
    print(characters, end="", flush=True)
    sleep(.1)

I tried the same on Pycharm it doesn't work, maybe Pycharm doesn't support flush. It only works when you use it on the terminal. Try running the same file through the terminal

No difference with or without flush. Python 3.9 Windows 10 Pro

I agree with this