docs: public IFeatureAlphabet buildFeatureAlphabet(String name,Type type)	{
  		IAlphabet alphabet = null;
  		if (!maps.containsKey(name))	{
  			IFeatureAlphabet fa;
  			if(type==Type.String)
  				fa = new StringFeatureAlphabet();
  			else if(type == Type.Integer)
  				fa = new HashFeatureAlphabet();
  			else
  				return null;
  			maps.put(name, fa);
  			alphabet = maps.get(name);
  		}else	{
  			alphabet = maps.get(name);
  			if (!(alphabet instanceof IFeatureAlphabet))	{
  				throw new ClassCastException();
  			}
  		}
  		return (IFeatureAlphabet) alphabet;
  	}