query: embed.html##Maps of all public library branches The Netherlands, layered by arbitrary groups of provinces 
  #
  #WDQs
  #Groningen	wd:Q752
  #Friesland	wd:Q770
  #Drenthe    wd:Q772
  #Overijssel	wd:Q773
  #Gelderland	wd:Q775
  #Flevoland	wd:Q707
  #Utrecht	wd:Q776
  #Noord-Holland	wd:Q701
  #Zuid-Holland	wd:Q694
  #Noord-Brabant	wd:Q1101
  #Zeeland	wd:Q705
  #Limburg	wd:Q1093
  #
  #defaultView:Map{"hide":["?dplLoc"],"layer":"?group"}
  
  SELECT DISTINCT ?dpl ?dplLabel ?dplImage ?dplLoc ?muniLabel ?provLabel ?group
  
  WHERE {
    ?dpl p:P31/ps:P31 wd:Q28564,wd:Q11396180;wdt:P17 wd:Q55. #public library branch in The Netherlands 
    ?dpl wdt:P625 ?dplLoc. #Geo location of the dpl
    OPTIONAL{?dpl wdt:P18 ?dplImage} #Image of the dpl} 
    
    #--- municipalities stuff----
    ?dpl wdt:P131 ?muni. #municipality derived from library item, has one single value
    ?muni p:P31 [ps:P31 ?muniIsA].
    VALUES ?muniIsA {wd:Q2039348}
    #Instead of the the above line, you can also do: FILTER(?muniIsA = wd:Q2039348) 
    #-- Province stuff
    ?muni wdt:P131 ?prov.  #find the province
    
    #Arbitrary groups of provinces 
    VALUES ?group1 {wd:Q701 wd:Q775 wd:Q772}
    VALUES ?group2 {wd:Q773 wd:Q1093 wd:Q694}
    VALUES ?group3 {wd:Q752 wd:Q770 wd:Q1101}
    VALUES ?group4 {wd:Q705 wd:Q707 wd:Q776}
       
    BIND(
      IF(?prov IN (?group1), "Groep 1",
      IF(?prov IN (?group2), "Groep 2",
      IF(?prov IN (?group3), "Groep 3",
      IF(?prov IN (?group4), "Groep 4",
      "")))) AS ?group).
    
    VALUES ?group {"Groep 1" "Groep 2" "Groep 3" "Groep 4"}
      
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en".}  
  }
  ORDER BY ?group