national flag (E50)

# try with SELECT ?s { ?s wdt:P31 wd:Q186516 } LIMIT 50

PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX wd: <http://www.wikidata.org/entity/>
PREFIX p: <http://www.wikidata.org/prop/>
PREFIX ps: <http://www.wikidata.org/prop/statement/>

start=@<national_flag>

<national_flag> EXTRA wdt:P31 {
  #must be an instance of at least national flag
  wdt:P31 [wd:Q186516];

  #must have a jurisdiction of country
  wdt:P1001 @<jurisdiction>;

  #must have an inception date
  wdt:P571 .;

  #must have an image
  wdt:P18 .;

  #must have one or more colours defined
  wdt:P462 @<colour>+;

  #must have a shape
  wdt:P1419 @<shape>;

  #must have an aspect ratio if the flag is rectangular
  (
    # flag is rectangular and must have an aspect ratio
    wdt:P1419 [wd:Q209];
    wdt:P2061 @<aspect_ratio>;
    |
    # flag is not rectangular and does not need to have an aspect ratio
    wdt:P1419 [. -wd:Q209];
  );

  #must have a Unicode flag character
  wdt:P487 LITERAL;

  #must have a Commons category
  wdt:P373 .;

  #must have a flags of the world ID
  wdt:P3089 LITERAL;

  #must have one or more designers (including the possibility of being set to unknown value)
  #TODO: handle unknown value
  wdt:P287 @<designer>+;

  #must depict one or more things (including the possibility of being set to unknown value or no value)
  #TODO: handle unknown value and no value
  wdt:P180 .+;
}

<jurisdiction> EXTRA wdt:P31 {
  #must be an instance of at least country
  wdt:P31 [wd:Q6256];
}

<colour> EXTRA wdt:P31 {
  #must be an instance of at least colour
  wdt:P31 [wd:Q1075];
}

<shape> EXTRA wdt:P31 {
  #must be an instance of at least geometric shape
  wdt:P31 [wd:Q815741];
}

<aspect_ratio> EXTRA wdt:P31 {
  #must be an instance of at least aspect ratio
  wdt:P31 [wd:Q20970434];
}

<designer> EXTRA wdt:P31 {
  #must be an instance of a person or organisation
  wdt:P31 [wd:Q5 wd:Q43229];
}