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);
    
  // parse lines into fragments & define entities
  
  if (nla.parsedLines == null) {
    new Matches m;
    nla.entities = linkedHashSet();
    nla.parsedLines = new L;
    MapSO wordTree = wordTree();
    
    for (int i = 0; i < l(nla.lines); i++) {
      S s = nla.lines.get(i);
      NLABlock.Line line = nla.new Line;
      line.text = s;
      line.proposition = parseToFragmentsUsingWordTree(s, wordTree);
      
      // define entity & extend word tree
      
      if "There is...|there are..." {
        S name = m.rest();
        NLABlock.Entity e = new(name, line);
        if (matchX2("a...|an...", name, m))
          e.addSynonym("the " + m.rest());
        nla.entities.add(e);
        addToWordTree_multi(wordTree, e.synonyms, e);
      }
      
      nla.parsedLines.add(line);
    }
  }
    
  ret nla;
}