Apologies if this topic has already been answered, but a quick search yielded no solution.

Ref: Novice to Ninja
File: chapter9/includes/access.inc.php (pg.302)
Function: userHasRole($role)

Can someone please explain to me where the value for the argument ($role) comes from in this function.
I thought values needed to be passed into functions via arguments included in the function call.
I can't see where $role has been declared or even a value for it.

Thanks in advance