tokenEq static method
Strict token equality: same word, a plural / es form of it, or a
number word and its digits. Never a prefix.
Implementation
static bool tokenEq(String a, String b) {
if (a == b) return true;
if (a == '${b}s' || b == '${a}s') return true;
if (a == '${b}es' || b == '${a}es') return true;
final ad = _numericWords[a];
if (ad != null && ad == b) return true;
final bd = _numericWords[b];
if (bd != null && bd == a) return true;
return false;
}