sbool swicEwic_trim(S s, S prefix, S suffix) {
  ret swic(s, prefix) && ewic(s, suffix);
}

sbool swicEwic_trim(S s, S prefix, S suffix, Matches m) {
  if (!swicEwic(s, prefix, suffix)) false;
  if (m != null)
    m.m = new S[] {trimSubstring(s, l(prefix), l(s)-l(suffix))};
  true;
}