Feature-based matching. Match if the given nodes have a variable called varName with zero value.
<fromRuleEltNumber,toRuleEltNumber>varz(varName);
fromRuleEltNumber - type: int
toRuleEltNumber - type: int
varName - type: string
# The example counts nouns that have a zero feature (i.e., node variable)
called "mass".
@PRE
<1,1> varz("mass");
@POST
++G("count nonmass nouns");
@RULES
_xNIL <-
_noun
@@
var, vareq, varne, PRE Actions