     expr matches as above, expr is saved under "label"
<li>#&lt;label:&gt;         any expr matches, and is saved under "label"
<li>#&lt;label&gt;          expr must match the value saved under "label"
<li>#&lt;...&gt;            skip exprs covered by the ellipsis
<li>#&lt;label:...&gt;      skip as above, saved skipped exprs under "label" as a quoted list.
<li>                  a pattern can have any number of labelled ellipses overall,
<li>                  but just one unnamed ellipsis, and only one ell