code: def create_license_helper(self, lic):
          
          if isinstance(lic, document.ExtractedLicense):
              return self.create_extracted_license(lic)
          if lic.identifier.rstrip('+') in config.LICENSE_MAP:
              return URIRef(lic.url)
          else:
              matches = [l for l in self.document.extracted_licenses if l.identifier == lic.identifier]
              if len(matches) != 0:
                  return self.create_extracted_license(matches[0])
              else:
                  raise InvalidDocumentError('Missing extracted license: {0}'.format(lic.identifier))
docs: Handle single(no conjunction/disjunction) licenses.
          Return the created node.