code: func (v *StyleContext) HasClass(className string) bool {
  	cstr := C.CString(className)
  	defer C.free(unsafe.Pointer(cstr))
  
  	return gobool(C.gtk_style_context_has_class(v.native(), (*C.gchar)(cstr)))
  }
docs: // HasClass is a wrapper around gtk_style_context_has_class().