python - How do I get a function inside of a while loop in a function to work properly? -

i have looked , looked answer, new python , answers find seem on head or not quite need. trying take code , turn multiple functions complete simple task of receiving grades user , displaying input user want it. more clear when see code.

import sys  gradelist = []  def validate_input():     try:         gradelist.append(int(grades))     except:         return false     else:         return true  def average(count, total):     ave = total / count     return ave  def exit(gradelist):     if gradelist == []:         print "you must enter @ least 1 grade program work. bye."         sys.exit()  #def get_info(): while true:     grades = raw_input("please input grades.(or enter once have entered of grades): ")     if not grades:         break     elif validate_input() == true:         continue     else:         print "please enter number."         continue  def give_answers(gradelist):         while true:         print "\n",         print "please select grades."         print "press 1 highest grade."         print "press 2 lowest grade."         print "press 3 average of grades entered."         print "\n",         print "or can press 'q' quit."         choice = raw_input("> ")         if choice == 'q':             break         elif choice == '1':             print "\n",             print "the highest grade entered %d.\n" % highest,         elif choice == '2':             print "\n",             print "the lowest grade entered %d.\n" % lowest,         elif choice == '3':             print "\n",             print "your average grade %d.\n" % average,         else:             print "please enter 1, 2, 3 or 'q'."   #get_info() exit(gradelist)  gradelist.sort() highest = gradelist[-1] lowest = gradelist[0] count = len(gradelist) total = sum(gradelist) average =  average( count, total)  give_answers(gradelist) 

everything works correctly have pasted code, when try define get_info nested validate_input() function stops working. no longer populates list exit() catches , ends program. loop seems pass on validate_input()function altogether because else statement trips after each time through. question how validate_input() function work while continuing accept input until user presses enter?

pass grade function validate_input add grade list like:

def validate_input(grades):