Returning a value

[moles]

Hello, I'm extremely new to programming and have been assigned this project for school. I'm at a point where I've become a little confused and was curious if any of you guys could point me in the right direction.

Where I am running into problems is in the move_forward(fuel) module. It computes the total for fuel but doesn't return it to the global variable. What is weird to me is the fire_wep(ammo) module, which visually looks almost identical to move_forward(fuel), works just fine and returns the deducted amount.

def main():
    ammo = 5
    fuel = 200
    
    print'This will give you control of your battlebot'
    print
    print'Menu Selections:'
    print'Enter 1 to Fire Weapon'
    print'Enter 2 to Move Forward'
    print'Enter 3 to Move Backwad'
    print'Enter 4 to Exit'
    choice(ammo, fuel)

def choice(ammo, fuel):
    
    print'Total amount of ammunition left',ammo
    print'Total amount of fuel left: ',fuel
    menu_choice = 0
    
    while menu_choice != 4:
        print
        menu_choice = input('Enter your choice of action: ')
        if menu_choice == 1:
            ammo = fire_wep(ammo)
        elif menu_choice == 2:
            move_forward(fuel)
        elif menu_choice == 3:
            move_backward()
        
    

def fire_wep(ammo):
    
    print ammo
    while ammo >= 1:
        print
        print'This is the amount of ammunition you have left',ammo
        distance = input('How far away is the target? ')
        if distance <= 20:
            print'The opponent is destroyed'
        elif distance <= 40:
            print'The opponent is partial disabled'
        elif distance >= 41:
            print'The opponent has not been damaged, get closer'
        ammo = ammo -1
        return ammo
    while ammo == 0:
        print'out of ammo'
    
        

def move_forward(fuel):
    feet = 0
    
    print fuel
    while fuel >= 1:
        print
        print'This is how much fuel you have left',fuel
        feet = input('Enter how may feet forward you want to move: ')
        if feet <= fuel:
            print'You have moved forward',feet
        elif feet >= fuel:
            print'You do not have enough fuel to proceed that distance'
            print'Please enter a smaller value'
        fuel = fuel - feet
        print fuel
        return fuel
    else:
        print'You are out of fuel'
    
main()

Any help is much appreciated.
Thanks, moles

[moles]

After sleeping on it, I figured it out. Forgot to set fuel = move_forward(fuel)