private async Task <Document> GetChangedDocumentCoreAsync(CancellationToken cancellationToken)
 {
     if (_isQueryLocal)
     {
         return(await _service.IntroduceQueryLocalAsync(_semanticDocument, _expression, _allOccurrences, cancellationToken).ConfigureAwait(false));
     }
     else if (_isLocal)
     {
         return(await _service.IntroduceLocalAsync(_semanticDocument, _expression, _allOccurrences, _isConstant, cancellationToken).ConfigureAwait(false));
     }
     else
     {
         return(await _service.IntroduceFieldAsync(_semanticDocument, _expression, _allOccurrences, _isConstant, cancellationToken).ConfigureAwait(false));
     }
 }
            private async Task <Document> IntroduceFieldAsync(CancellationToken cancellationToken)
            {
                var result = await _service.IntroduceFieldAsync(_document, _expression, _allOccurrences, _isConstant, cancellationToken).ConfigureAwait(false);

                return(result.Item1);
            }