pub type PFNGLPROGRAMUNIFORM2FPROC = Option<unsafe extern "C" fn(program: GLuint, location: GLint, v0: GLfloat, v1: GLfloat)>;
pub enum PFNGLPROGRAMUNIFORM2FPROC { None, Some(unsafe extern "C" fn(u32, i32, f32, f32)), }
No value.
Some value of type T.
T