code: def id(self):
          
          def normalize(distro_id, table):
              distro_id = distro_id.lower().replace(' ', '_')
              return table.get(distro_id, distro_id)
  
          distro_id = self.os_release_attr('id')
          if distro_id:
              return normalize(distro_id, NORMALIZED_OS_ID)
  
          distro_id = self.lsb_release_attr('distributor_id')
          if distro_id:
              return normalize(distro_id, NORMALIZED_LSB_ID)
  
          distro_id = self.distro_release_attr('id')
          if distro_id:
              return normalize(distro_id, NORMALIZED_DISTRO_ID)
  
          distro_id = self.uname_attr('id')
          if distro_id:
              return normalize(distro_id, NORMALIZED_DISTRO_ID)
  
          return ''
docs: Return the distro ID of the OS distribution, as a string.
  
          For details, see :func:`distro.id`.