Function lua_tounsignedx 

pub unsafe extern "C-unwind" fn lua_tounsignedx(
    L: *mut lua_State,
    idx: c_int,
    isnum: *mut c_int,
) -> lua_Unsigned

Attempts to convert the value at the given index to an unsigned integer.

This function operates in the exact same way as lua_tointegerx, but returns a lua_Unsigned instead of a lua_Integer. If the value is negative the output is undefined.