static ItIt<Matches> flexMatchIC_iterator(S pat, S input) {
  L<S> tokPat = javaTokNPunctuation_plusAsterisk(pat), tokInput = javaTokNPunctuation_plusAsterisk(input);
  ret flexMatchIC_iterator(pat, tokPat, tokInput);
}
  
static ItIt<Matches> flexMatchIC_iterator(Tok pat, Tok input) {
  ret flexMatchIC_iterator(pat.text(), pat.tok(), input.tok());
}

static ItIt<Matches> flexMatchIC_iterator(S pat, LS tokPat, LS tokInput) {
  L<Int> varIndices = flexMatchIC_getVarIndices(tokPat, tokInput);
  if (varIndices == null) ret emptyItIt();

  ItIt<LS> spreadInputs = ai_spreadCertainIndices_2_iterator(tokPat, tokInput, varIndices);
  
  ret mapI_notNulls(tok -> getMatches(pat, tok), spreadInputs);
}

Began life as a copy of #1021059