Python Grade Average

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#==============MODULES================#
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#=====================================#
#==============VARIABLES==============#
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menus = ["(1) Execute ", "(2) Exit   "]
num = 0

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#==============FUNCTIONS==============#
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#define menu
def menu(parameter):
    print "     +===========+"
    print "     |    MENU   |"
    print "     |-----------|"
    for word in parameter:
        print "     |%s|" % word
        print "     |-----------|"

#define average of exams
def avg(num):
    test_count = input("Please enter the number of grades to average: ")
    for counts in range(test_count):
        num_grade = input("Please enter a grade value: ")
        num = (num_grade + num)
        if counts == (test_count - 1):
            nums = (num / test_count)
            print "Your grade is: %s Percent" % nums

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#=============MAIN PROGRAM============#
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def main():
    menu(menus)
    choice = input("Please make a selection(1-2): ")

    if choice == 1:
        avg(num)
    elif choice == 2:
        print "Exiting Program. Goodbye"
        return
    else:
        print "Invalid Selection"
        return main()