code: func makeCFString(str string) C.CFStringRef {
  	s := C.CString(str)
  	defer C.free(unsafe.Pointer(s))
  	return C.CFStringCreateWithCString(C.kCFAllocatorDefault, s, C.kCFStringEncodingUTF8)
  }
docs: // makeCFString makes an immutable string with CFStringCreateWithCString.