private TagDirectiveCollection NonDefaultTagsAmong(IEnumerable<TagDirective> tagCollection) { var directives = new TagDirectiveCollection(); if (tagCollection == null) return directives; foreach (var tagDirective in tagCollection) { AppendTagDirectiveTo(tagDirective, false, directives); } foreach (var tagDirective in Constants.DefaultTagDirectives) { directives.Remove(tagDirective); } return directives; }