"""
A simple program, that gets an integer from the user,
and prints the result of multiplying that integer by 2.
If the user did not enter a valid integer, the system keeps asking.

THIS VERSION OF THE PROGRAM USES THE check_integer FUNCTION
"""

from number_check import *

while True:
    text = input("please enter an integer: ")
    if (check_integer(text) == True):
        break
        
number = int(text)
print(number * 2)