clojure.lang.PushbackTextReader.Unread C# (CSharp) Method

        public virtual void Unread(int ch)
        {
            if (_hasUnread)
                throw new IOException("Can't unread a second character.");

            _unreadChar = ch;
            _hasUnread = true;
        }

 static void Unread(PushbackTextReader r, int ch)
 {
     if (ch != -1)
     {
         r.Unread(ch);
     }
 }