You're seeing just the function forage_horizontal_form_group, go back to ForageWeb.ForageView module for more information.
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forage_horizontal_form_group(form, field, label, error_helpers, opts, input_fun)

Horizontal form group with support for internationalization by taking in the application's error_helpers module.

You shouldn't need to use this function directly. You can use the ForageWeb.ForageView.forage_form_group/5 callback defined in your view module, which impoements a specialized version of this function using your application's error_helpers module.