Python Generate Unique Username

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#==============MODULES================#
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#==============VARIABLES==============#
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menus = ["(1) Create Username", "(2) Exit           "]
usernameList = []

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#==============FUNCTIONS==============#
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#defines menu
def menu(paramter):
    print "     +===================+"
    print "     |       Menu        |"
    print "     |-------------------|"
    for word in parameter:
        print "     |%s|" % word
        print "     |-------------------|"

#creates username and checks to see if name is already taken
def usr(usernameList):
    firstname = raw_input("Please enter your first name: ").lower()
    lastname = raw_input("Please enter your last name: ").lower()
    #create username First character in firstname and and characters 6 characters from lastname
    username = firstname[0] + lastname[:7]
    #username check
    if username in usernameList:
        print "The username %s is not available." % username
        print
        num = input("Please enter a number(1-9): ")
        new_username = (firstname[0] + lastname[:6] + str(num))
        #add "new_username" to list
        usernameList.append(new_username)
        print "The username %s has been created." % new_username
    else:
        #add "username" to list
        usernameList.append(username)
        print "The username %s has been created." % username

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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:
        usr(usernameList)
    elif choice ==2:
        print "Exiting Program. Goodbye"
        return
    else:
        print "Invalid Selection"
        return main()