code: def _getSimplePassage(self, reference=None):
          
          if reference is None:
              return _SimplePassage(
                  resource=self.resource,
                  reference=None,
                  urn=self.urn,
                  citation=self.citation.root,
                  text=self
              )
  
          subcitation = self.citation.root[reference.depth-1]
          resource = self.resource.xpath(
              subcitation.fill(reference),
              namespaces=XPATH_NAMESPACES
          )
  
          if len(resource) != 1:
              raise InvalidURN
  
          return _SimplePassage(
              resource[0],
              reference=reference,
              urn=self.urn,
              citation=subcitation,
              text=self.textObject
          )
docs: Retrieve a single node representing the passage.
  
          .. warning:: Range support is awkward.
  
          :param reference: Identifier of the subreference / passages
          :type reference: list, reference
          :returns: Asked passage
          :rtype: CapitainsCtsPassage