Returns the current fuel level of the turtle, this is the same integer returned by turtle.getFuelLevel(),
that decreases by 1 every time the turtle moves.
Returns the numerical ID of this computer.
This is the same number obtained by calling os.getComputerID() or running the "id" program from lua,
and is guarunteed unique.
Unmounts a directory previously mounted onto the computers file system by mount or mountWritable.
When a directory is unmounted, it will disappear from the computers file system, and the user will no longer be able to
access it.