Function Lpush_where 

pub unsafe extern "C" fn Lpush_where(state: lua_State, level: i32)

Pushes onto the stack a string identifying the current position of the control at level level in the call stack. Typically this string has the following format:

    chunkname:currentline:

Level 0 is the running function, level 1 is the function that called the running function, etc.

This function is used to build a prefix for error messages.