Gather nodes that matched the current element under a single node with NAME as its name.
group is an alternative form for gp. gp is analogous to the group Post Action.
# Do a mini-reduction of all the nodes that matched _noun, naming the
reduce node _nouns,
# before reducing the entire pattern to an _np.
_np <- _det _quan _adj _noun [plus group=_nouns] @@
rename, Phrase Element Modifiers.