"""
 try_changing_number.py
 
 try to change a variable in place. Fail.
 
   $ python try_changing_number.py
   in main : n is  10
     in double in place - the number is  10
     in double_in_place - the new number is  20
   in main : n is now  10
 
"""

def double_in_place(number):
    """ try to change the variable in the calling routine """
    print(" in double in place - the number is ", number)
    number = 2 * number
    print(" in double_in_place - the new number is ", number)

          
def main():
    n = 10
    print("in main : n is ", n)
    double_in_place(n)   # this does not change n !
    print("in main : n is now ", n)
    
main()