code: func GetSubroutineIndex(program uint32, shadertype uint32, name *uint8) uint32 {
  	ret := C.glowGetSubroutineIndex(gpGetSubroutineIndex, (C.GLuint)(program), (C.GLenum)(shadertype), (*C.GLchar)(unsafe.Pointer(name)))
  	return (uint32)(ret)
  }
docs: // retrieve the index of a subroutine uniform of a given shader stage within a program