Function GDNativeLibrary.singleton
If true, Godot loads the library at startup rather than the first time a script uses the library, calling {prefix}gdnative_singleton after initializing the library (where {prefix} is the value of symbolPrefix). The library remains loaded as long as Godot is running.
Note: A singleton library cannot be reloadable.
bool singleton() nothrow @property @nogc;
void singleton
(
bool v
) nothrow @property @nogc;