["python","syntax"]
Python, what does an underscore before parenthesis do

Looking through some of the Django code in authentication forms I noticed the following syntax: label=_("Username") Normally I would have just used a pair of quotes around the string. Can someone explain what the underscore and parenthesis around "Username" do?
The _ is the name of a callable (function, callable object). It's usually used for the gettext function, for example in Django: from django.utils.translation import gettext as _ print _("Hello!") # Will print Hello! if the current language is English # "Bonjour !" in French # ¡Holà! in Spanish, etc. As the doc says: Python’s standard library gettext module installs _() into the global namespace, as an alias for gettext(). In Django, we have chosen not to follow this practice, for a couple of reasons: [...] The underscore character (_) is used to represent “the previous result” in Python’s interactive shell and doctest tests. Installing a global _() function causes interference. Explicitly importing gettext() as _() avoids this problem. Even if it's a convention, it may not be the case in your code. But be reassured, 99.9% of the time _ is an alias for gettext :)