public DestroyNotify g_free
Frees the memory pointed to by
If you know the allocated size of
mem, calling free_sized may be
faster, depending on the libc implementation in use.
Starting from GLib 2.78, this may happen automatically in case a GCC compatible compiler is used with some optimization level and the allocated size is known at compile time (see [documentation of `__builtin_object_size()`](https://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html) to understand its caveats).
mem is null it simply returns, so there is no need to check
null before calling this function.
the memory to free