query: #title: Check main value of voice type
  # Complex constraint from [[Property talk:P4407]]
  #
  SELECT DISTINCT ?item ?value ?voiceType {
      ?item wdt:P4407 ?value .
      ?item wdt:P412 ?voiceType.
      BIND(STRBEFORE(?value, "/") as ?before).
      FILTER regex(?value, "^.+\\/+.")
      FILTER(! (?before = 'sopranos' && (?voiceType = wd:Q30903 || ?voiceType = wd:Q58192) ))
      FILTER(! (?before = 'baritones' && ?voiceType = wd:Q31687))
      FILTER(! (?before = 'tenors' && (?voiceType = wd:Q27914 || ?voiceType = wd:Q6141658 || ?voiceType = wd:Q3983766 || ?voiceType = wd:Q1471878) ))
      FILTER(! (?before = 'countertenors' && ?voiceType = wd:Q223166))
      FILTER(! (?before = 'basses' && ?voiceType = wd:Q27911))
      FILTER(! (?before = 'mezzo-sopranos' && ?voiceType = wd:Q186506))
      FILTER(! (?before = 'contraltos' && ?voiceType = wd:Q37137))   
  } ORDER BY ?item