17                 if (args.length != 1) {
 
   18                         throw new ValueExprEvaluationException(getURI() + 
" requires exactly 1 arguments, got " + args.length);
 
   20                 LiteralType l=LiteralRegistry.getLiteral(((Literal)args[0]).getDatatype().toString());
 
   21                 if(l instanceof RasterLiteral) {
 
   22                         GridCoverage geom=((RasterLiteral)l).read(args[0].stringValue());
 
   23                         GridCoverage result = 
modify(geom);
 
   24                         return valueFactory.createLiteral(((RasterLiteral) l).unparse(result),((Literal)args[0]).getDatatype());
 
abstract GridCoverage modify(GridCoverage coverage)