Sets the debugging hook function.
For each event, the hook is called as explained below: * The call hook: is called when the interpreter calls a function. The hook is called just after Lua enters the new function, before the function gets its arguments. * The return hook: is called when the interpreter returns from a function. The hook is called just before Lua leaves the function. You have no access to the values to be returned by the function. * The line hook: is called when the interpreter is about to start the execution of a new line of code, or when it jumps back in the code (even to the same line). (This event only happens while Lua is executing a Lua function.) * The count hook: is called after the interpreter executes every count instructions. (This event only happens while Lua is executing a Lua function.) A hook is disabled by setting mask to zero.