pub type PFNGLUNIFORM3FARBPROC = Option<unsafe extern "C" fn(location: GLint, v0: GLfloat, v1: GLfloat, v2: GLfloat)>;
enum PFNGLUNIFORM3FARBPROC { None, Some(unsafe extern "C" fn(_: i32, _: f32, _: f32, _: f32)), }
No value.
Some value of type T.
T