static NLABlock nla_parse(S text) {
  ret nla_parse(new NLABlock(text));
}
  
// fills and returns original object
static NLABlock nla_parse(NLABlock nla) {
  // parse into lines (or sentences, both is OK)
  if (nla.lines == null)
    nla.lines = sentencesOrLines(nla.text);
    
  // get entities
  if (nla.entities == null) {
    new Matches m;
    nla.entities = linkedHashSet();
    for (S s : nla.lines)
      if "There is...|there are..."
        nla.entities.add(new NLABlock.Entity(m.rest(), s));
  }
}