protected static SignatureHelpItems CreateSignatureHelpItems(
            IEnumerable<SignatureHelpItem> items, TextSpan applicableSpan, SignatureHelpState state)
        {
            if (items == null || !items.Any() || state == null)
            {
                return null;
            }

            items = Filter(items, state.ArgumentNames);
            return new SignatureHelpItems(items.ToList(), applicableSpan, state.ArgumentIndex, state.ArgumentCount, state.ArgumentName);
        }
        protected static SignatureHelpItems CreateSignatureHelpItems(
            IEnumerable <SignatureHelpItem> items, TextSpan applicableSpan, SignatureHelpState state)
        {
            if (items == null || !items.Any() || state == null)
            {
                return(null);
            }

            items = Filter(items, state.ArgumentNames);
            return(new SignatureHelpItems(items.ToList(), applicableSpan, state.ArgumentIndex, state.ArgumentCount, state.ArgumentName));
        }