@Araq: I guess that explains most of the apparently whimsical behaviour pointed
at in rule 12, if not all. Have to rethink `{`}echo___echo{`}` (wrong) vs
`{`}echo_echo{`}` (right, collapses to `echoecho`) vs `{`}!___!{`}` (right,
collapses to `{`}!!{`}`). Still don't see that one.Only 11 rules to go. :)
