+ """Parse arguments, perform the action, write useful output, propagate RC.
+
+ If the intended action is cancellation, reservation dir is deleted.
+
+ If the intended action is reservation, the list is longer:
+ 1. List contents of reservation dir.
+ 2. List contents of test.url file in the dir.
+ 3. Create reservation dir.
+ 4. Touch file according to -r option.
+ 5. Put -u option string to file test.url
+ From these 5 steps, 1 and 2 are performed always, their RC ignored.
+ RC of step 3 gives the overall result.
+ If the result is success, steps 4-5 are executed without any output,
+ their RC is ignored.
+
+ The two files in reservation dir are there for reporting
+ which test run holds the reservation, so people can manually fix the testbed
+ if the rest run has been aborted, or otherwise failed to unregister.
+
+ The two files have different audiences.
+
+ The URL content is useful for people scheduling their test runs
+ and wondering why the reservation takes so long.
+ For them, a URL (if available) to copy and paste into browser
+ to see which test runs are blocking testbeds is the most convenient.
+
+ The "run tag" as a filename is useful for admins accessing the testbed
+ via a graphical terminal, which does not allow copying of text,
+ as they need less keypresses to identify the test run holding the testbed.
+ Also, the listing shows timestamps, which is useful for both audiences.
+ """