+* man: maybe use the word "inspect" rather than "introspect"?
+
+* introduce machines.target to order after all nspawn instances
+
+* systemd-nspawn@.service should fail if some nspawn arg is invalid, with Type=notify
+
+* "machinectl list" should probably show columns for OS version and IP addresses
+
+* systemctl: if it fails, show log output?
+
+* maybe add "systemctl edit" that copies unit files from /usr/lib/systemd/system to /etc/systemd/system and invokes vim on them
+