in fact I usually avoid inheritance, my normal implementation for something like that would be a dedicated module named `forms` and would do: `forms.fill(this.form, { startDate: value })` but since we are using inheritance for the other features like `displayed` and `waitForDisplay` we can just keep putting shared behavior on the `parent.prototype`.

things like `this.foo.bar.long.namespace` are usually a red flag. - means you know too much about inner structure and that you should probably split things into discrete modules.