public Argument evaluate(ContextStack context, Argument arg1, Argument arg2)
public Argument evaluate(ContextStack context, ArrayList args)
	public Argument evaluate(ContextStack context, Argument arg1, Argument arg2)		throws MapyrusException	{		Argument retval;		String wkt1 = arg1.toString();		String wkt2 = arg2.toString();		/*		 * If one of the geometries is nothing, then just return the other		 * value.		 */		if (wkt1.length() == 0)		{			retval = arg2;		}		else if (wkt2.length() == 0)		{			retval = arg1;		}		else		{			try			{				Geometry g1 = new WKTReader().read(wkt1);				Geometry g2 = new WKTReader().read(wkt2);				Geometry union = g1.union(g2);				retval = new Argument(union.toText());			}			catch (ParseException e)			{				throw new MapyrusException(e.getMessage());			}			catch (IllegalArgumentException e)			{				throw new MapyrusException(e.getMessage());			}		}		return(retval);	}