code: def parse_only_extr_license(self, extr_lic):
          
          # Grab all possible values
          ident = self.get_extr_license_ident(extr_lic)
          text = self.get_extr_license_text(extr_lic)
          comment = self.get_extr_lics_comment(extr_lic)
          xrefs = self.get_extr_lics_xref(extr_lic)
          name = self.get_extr_lic_name(extr_lic)
  
          if not ident:
              # Must have identifier
              return
  
          # Set fields
          # FIXME: the constructor of the license should alwas accept a name
          lic = document.ExtractedLicense(ident)
          if text is not None:
              lic.text = text
          if name is not None:
              lic.full_name = name
          if comment is not None:
              lic.comment = comment
          lic.cross_ref = map(lambda x: six.text_type(x), xrefs)
          return lic
docs: Return an ExtractedLicense object to represent a license object.
          But does not add it to the SPDXDocument model.
          Return None if failed.