code: public List<SpannedExpression> getSpannedLogicalForms() {
      List<SpannedExpression> spannedExpressions = Lists.newArrayList();
      getSpannedLogicalFormsHelper(spannedExpressions);
      return spannedExpressions;
    }
docs: Gets the logical forms for every subspan of this parse tree.
  Many of the returned logical forms combine with each other
  during the parse of the sentence.
  
  @return