Demonstration of an issue I am seeing with Dart Mustache templating

templateTest.dart

import 'package:mustache/mustache.dart' as mustache;

void main() {

  var legSet = [{'legnumber': 207, 'is_last': false}, {'legnumber': 208, 'is_last': false}, {'legnumber': 209, 'is_last': false}, {'legnumber': 210, 'is_last': true}];

  var source = ("""
      SELECT DISTINCT  ?slice 
      FROM <http://data.oceandrilling.org/janus/>
      WHERE {
      {{#legs}}  { ?sliceKey iodp:leg "{{legnumber}}" . } {{^is_last}} UNION {{/is_last}}  {{/legs}}
      ?sliceKey iodp:site "1226" .
      ?slice  qb:sliceStructure <http://data.oceandrilling.org/janus/sliceByvcd_image> .
      ?slice qb:sliceStructure ?sliceKey .
      }
  """);

  var template = mustache.parse(source);
  var output = template.renderString({'legs': legSet});
  print(output);

  var source2 = ("""
      SELECT DISTINCT  ?slice 
      FROM <http://data.oceandrilling.org/janus/>
      WHERE (
      {{#legs}}  ( ?sliceKey iodp:leg "{{legnumber}}" . ) {{^is_last}} UNION {{/is_last}}  {{/legs}}
      ?sliceKey iodp:site "1226" .
      ?slice  qb:sliceStructure <http://data.oceandrilling.org/janus/sliceByvcd_image> .
      ?slice qb:sliceStructure ?sliceKey .
      )
  """);

  var template2 = mustache.parse(source2);
  var output2 = template2.renderString({'legs': legSet});
  print(output2);

}

this is not an issue.. an old version of the library had this issue, it's been long resolved