System.Xml.Schema.SymbolsDictionary.AddWildcard C# (CSharp) Method

        private void AddWildcard(string wildcard, object particle) {
            if (wildcards == null) {
                wildcards = new Hashtable();
            }
            object lookup = wildcards[wildcard];
            if (lookup == null) {
                wildcards.Add(wildcard, last);
                particles.Add(particle);
                Debug.Assert(particles.Count == last + 1);
                last ++;
            }
            else if (particle != null) {
                particles[(int)lookup] = particle;    
            }
        }