1. No string concatenation should be used in the gettext function.
2. Some extra parentheses should be used in coffee script, to avoid the following situation: in coffee script, the call ```gettext "text to be extracted" + "text should not be extracted"``` will be translated into ```gettext("text to be extracted" + "text should not be extracted")``` rather than ```gettext("text to be extracted") + "text should not be extracted"```.