int?ParseSdkVersion(XAttribute attribute)
        {
            var version = (string)attribute;

            if (string.IsNullOrEmpty(version))
            {
                return(null);
            }
            int vn;

            if (!int.TryParse(version, out vn))
            {
                int?apiLevel = versions.GetApiLevelFromId(version);
                if (apiLevel.HasValue)
                {
                    return(apiLevel.Value);
                }
                return(versions.MaxStableVersion.ApiLevel);
            }
            return(vn);
        }