How to initialize an argument?

I am working on 1.5 of my SmartTurtleOS, and implementing the feature so you can tell the turtle how many blocks to move.

function smartMoveForward(distance)
for i=1,distance do
...

How do I set distance to "1" by default in case they enter "smartMoveForward()"

distance = distance or 1

local distance = distance or 1

EDIT: :ph34r:/>'d

This works because when distance is nil (that is, when the user did not enter any value), it evaluates to false in an expression. Since it evaluates to false, Lua continues along the expression to 1 and assigns that to distance instead. If distance is not nil (that is, if the user did enter a value), it will evaluate to true, and Lua will ignore the remainder of the expression.

You can do something like
if not distance then distance = 1 end
that sets distance to 1 if distance is nil
maybe this would work too, although im not sure.. distance = distance or 1


Edit: double ninja'd :P/>