code: function retroflex_k(hash) {
      var stemh = hash.stem.replace(/क्$/, 'ह्');
      var stemz = hash.stem.replace(/क्$/,'ष्');
      var stemj = hash.stem.replace(/क्$/,'ज्');
      var stemc = hash.stem.replace(/क्$/,'च्');
      if (stemh == hash.stem && stemz == hash.stem  && stemj == hash.stem) return;
      hash.stems = [stemh, stemz, stemj, stemc];
      if (debug) log('mod: retroflex_k', hash.stems);
  }
docs: flex_starts_z && cflex_starts_s && stem_ends_k