Review pushing FILTERs into sequences

The code isn't doing the best it could (see below).

This maybe just because SERVICE is involved. The code needs review for when it takes place in the optimization processes and which forms if can push filters over.

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX dbo: <http://dbpedia.org/ontology/>

SELECT *
WHERE {

?country a dbo:Country .
?country owl:sameAs ?wbcountry .
FILTER (regex(str(?wbcountry), "^http://worldbank.270a.info/"))
SERVICE <http://worldbank.270a.info/sparql>

{ ?wbcountry skos:prefLabel ?label }

}