static bool endsWith(S a, S b) {
  ret a != null && a.endsWith(b);
}

static bool endsWith(S a, char c) {
  ret nempty(a) && lastChar(a) == c;
}

ifclass Matches
  static bool endsWith(S a, S b, Matches m) {
    if (!endsWith(a, b)) false;
    m.m = new S[] {dropLast(l(b), a)};
    true;
  }
endif