deb http://http.debian.net/debian buster-backports main contrib non-free
deb-src http://http.debian.net/debian buster-backports main contrib non-free
+
+deb http://http.us.debian.org/debian unstable main contrib non-free
+deb-src http://http.us.debian.org/debian unstable main contrib non-free
+
+deb http://http.us.debian.org/debian experimental main
+deb-src http://http.us.debian.org/debian experimental main