How to make a command undoable in one step?

[Marcin Borkowski]

Hi all,

so I have this command of mine which does a few `insert's, but I'd like
it to be undoable in one step.  How do I achieve that?  I noticed that
adding `undo-auto-amalgamate' at the beginning (almost) does the trick,
but then consecutive calls of this command are, well, amalgamated into
one undo step, which I don't like.  So I explicitly call `undo-boundary'
at the end of the command.  This works, but after some thought I guess
there must be a better way.  Any hints?

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University