pub type PFNGLBINDMULTITEXTUREEXTPROC = Option<unsafe extern "C" fn(texunit: GLenum, target: GLenum, texture: GLuint)>;
enum PFNGLBINDMULTITEXTUREEXTPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: u32)), }
No value.
Some value of type T.
T