final List<TransferPair> transfers = Lists.newArrayList();
final ClassGenerator<Filterer> cg = CodeGenerator.getRoot(Filterer.TEMPLATE_DEFINITION2, context.getFunctionRegistry());
final LogicalExpression expr = ExpressionTreeMaterializer.materialize(popConfig.getExpr(), incoming, collector, context.getFunctionRegistry());
if(collector.hasErrors()){
throw new SchemaChangeException(String.format("Failure while trying to materialize incoming schema. Errors:\n %s.", collector.toErrorString()));
}
cg.addExpr(new ReturnValueExpression(expr));
for(VectorWrapper<?> v : incoming){