rule.spad line 238 [edit on github]
A ruleset is a set of pattern matching rules grouped together.
elt(r, f, n) or r(f, n) applies all the rules of r to f at most n times.
rules(r) returns the rules contained in r.
ruleset([r1, ..., rn]) creates the rule set r1, ..., rn.
Eltable(F, F)