Only use one-off var if it significantly improves code clarity.  In this case it doesn't and makes it harder because there is a separation of where a variable is defined and where it is used.  I guess this is intended as a pseudo-configuration variable at the top of the function, but there is no point in configuring like this when hardwired within an installed module.  If it really needs to be changed (probably not) then it should be a function arg.