Argument arg1 = (Argument)args.get(0);
	public Argument evaluate(ContextStack context, Argument arg1)		throws MapyrusException	{		Argument retval;		try		{			/*			 * Calculate convex hull for geometry.			 */			String wkt1 = arg1.toString();			Geometry g1 = new WKTReader().read(wkt1);			com.vividsolutions.jts.algorithm.ConvexHull hull = new				com.vividsolutions.jts.algorithm.ConvexHull(g1);			retval = new Argument(hull.getConvexHull().toText());		}		catch (ParseException e)		{			throw new MapyrusException(e.getMessage());		}		catch (IllegalArgumentException e)		{			throw new MapyrusException(e.getMessage());		}		return(retval);	}