How to set or change "Loading" text?

Sometimes, when loading a page, I see a “Loading” label appear.

I attach a screenshot of this…

How can I set or change this “Loading” text?

Thanks to the gitter.im room,
I learnt that (at least for the code that I’ve inherited)
the source of the Loading message is Iron Router…
https://github.com/iron-meteor/iron-router/blob/devel/lib/hooks.js

I’m able to tweak the Loading message via the loadingTemplate attribute of Iron Router, cf https://iron-meteor.github.io/iron-router/#the-waiton-option