code: def to_json(self):
          
          titles = self.get_titles()
          return json.dumps({
                  "uri" : self.subject
                  , "urn" : str(self.get_urn())
                  , "titles" : [{"language":lang, "label":label} for lang, label in titles]
                  , "title_abbreviations" : self.get_abbreviations()
  
              }, indent=2)
docs: Serialises a HucitWork to a JSON formatted string.