CC turtle control

local call
local button = 0

print("W,A,S,D,Q,E - control. R - refuel. Z - DigDown. X - Dig. C - DigUp. F = exit")
while true do
while call ~= "char" do
call, button = os.pullEvent()
end

    if button == 'w' then
        turtle.forward()
    end

    if button == 's' then
        turtle.back()
    end

    if button == 'a' then
        turtle.turnLeft()
    end

    if button == 'd' then
        turtle.turnRight()
    end

    if button == 'q' then
        turtle.down()
    end

    if button == 'e' then
        turtle.up()
    end

    if button == 'f' then
        return 0
    end

    if button == 'r' then
        turtle.refuel()
    end

    if button == 'z' then
        turtle.digDown()
    end

    if button == 'x' then
        turtle.dig()
    end

    if button == 'c' then
        turtle.digUp()
    end

    call = ""
    button = 0
end