pub type PFNGLGETVERTEXATTRIBIUIVPROC = Option<unsafe extern "C" fn(index: GLuint, pname: GLenum, params: *mut GLuint)>;
enum PFNGLGETVERTEXATTRIBIUIVPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: *mut u32)), }
No value.
Some value of type T.
T