[Answered ]-What does an '_' in django url do?

_ is often a shortcut for a gettext function that will produce a localized version of the string. It’s unusual to do it for URLs, but it’s documented: https://docs.djangoproject.com/en/1.11/topics/i18n/translation/#translating-url-patterns

At the top of the file you might find something like:

from django.utils.translation import ugettext as _