public void Save(string filepath)
        {
            string path = filepath;

            if (String.IsNullOrEmpty(Path.GetExtension(filepath)))
            {
                path = $"{filepath}.config";
            }

            _fileWrapper.CreateBackup(path);

            var    fi   = new FileInfo(path);
            string json = JsonConvert.SerializeObject(new List <VariableInfo>(_variableLookup.Values));

            _fileWrapper.Write(fi.FullName, json);
        }