PREFIX : <#>
PREFIX adms: <http://www.w3.org/ns/adms#>
PREFIX adres: <https://data.vlaanderen.be/ns/adres#>
PREFIX besluit: <http://data.vlaanderen.be/ns/besluit#>
PREFIX crypto: <http://www.w3.org/2000/10/swap/crypto#>
PREFIX e: <http://eulersharp.sourceforge.net/2003/03swap/log-rules#>
PREFIX ex: <http://example.org/test#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX func: <http://www.w3.org/2007/rif-builtin-function#>
PREFIX generiek: <https://data.vlaanderen.be/ns/generiek#>
PREFIX log: <http://www.w3.org/2000/10/swap/log#>
PREFIX mandaat: <http://data.vlaanderen.be/ns/mandaat#>
PREFIX mu: <http://mu.semte.ch/vocabularies/core/>
PREFIX org: <http://www.w3.org/ns/org#>
PREFIX persoon: <https://data.vlaanderen.be/ns/persoon#>
PREFIX persoon_loket: <http://data.vlaanderen.be/ns/persoon#>
PREFIX skos:<http://www.w3.org/2004/02/skos/core#>
PREFIX string: <http://www.w3.org/2000/10/swap/string#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

# Retract empty strings
{
  {
    ?s ?p ""
  } e:becomes {}.
} => {}.