control

while true do
  _,key = os.pullEvent("char")
  if key == "r" then
    turtle.refuel()
  elseif key == "w" then
    turtle.forward()
  elseif key == "s" then
    turtle.back()
  elseif key == "a" then
    turtle.turnLeft()
  elseif key == "d" then
    turtle.turnRight()
  elseif key == "q" then
    turtle.down()
  elseif key == "e" then
    turtle.up()
  elseif key == "z" then
    turtle.digDown()
  elseif key == "x" then
    turtle.dig()
  elseif key == "c" then
    turtle.digUp()
  elseif key == "v" then
    turtle.placeDown()
  elseif key == "b" then
    turtle.place()
  elseif key == "n"  then
    turtle.placeUp()
  elseif tonumber(key) + 0 == tonumber(key) then
    turtle.select(tonumber(key))
  end
end