docs: def _clean_value(key, val):
      '''
      Clean out well-known bogus values.
      If it isn't clean (for example has value 'None'), return None.
      Otherwise, return the original value.
  
      NOTE: This logic also exists in the smbios module. This function is
            for use when not using smbios to retrieve the value.
      '''
      if (val is None or not val or
              re.match('none', val, flags=re.IGNORECASE)):
          return None
      elif 'uuid' in key:
          # Try each version (1-5) of RFC4122 to check if it's actually a UUID
          for uuidver in range(1, 5):
              try:
                  uuid.UUID(val, version=uuidver)
                  return val
              except ValueError:
                  continue
          log.trace('HW %s value %s is an invalid UUID', key, val.replace('\n', ' '))
          return None
      elif re.search('serial|part|version', key):
          # 'To be filled by O.E.M.
          # 'Not applicable' etc.
          # 'Not specified' etc.
          # 0000000, 1234567 etc.
          # begone!
          if (re.match(r'^[0]+$', val) or
                  re.match(r'[0]?1234567[8]?[9]?[0]?', val) or
                  re.search(r'sernum|part[_-]?number|specified|filled|applicable', val, flags=re.IGNORECASE)):
              return None
      elif re.search('asset|manufacturer', key):
          # AssetTag0. Manufacturer04. Begone.
          if re.search(r'manufacturer|to be filled|available|asset|^no(ne|t)', val, flags=re.IGNORECASE):
              return None
      else:
          # map unspecified, undefined, unknown & whatever to None
          if (re.search(r'to be filled', val, flags=re.IGNORECASE) or
                  re.search(r'un(known|specified)|no(t|ne)? (asset|provided|defined|available|present|specified)',
                      val, flags=re.IGNORECASE)):
              return None
      return val