code: def _missing_(cls, value):
          
          if not (isinstance(value, int) and 0x0000 <= value <= 0xFFFF):
              raise ValueError('%r is not a valid %s' % (value, cls.__name__))
          if 0x0001 <= value <= 0x0BB8:
              extend_enum(cls, 'Registered by Xerox [0x%s]' % hex(value)[2:].upper().zfill(4), value)
              return cls(value)
          if 0x0020 <= value <= 0x003F:
              extend_enum(cls, 'Experimental [0x%s]' % hex(value)[2:].upper().zfill(4), value)
              return cls(value)
          if 0x0BB9 <= value <= 0xFFFF:
              extend_enum(cls, 'Dynamically Assigned [0x%s]' % hex(value)[2:].upper().zfill(4), value)
              return cls(value)
          if 0x4000 <= value <= 0x4FFF:
              extend_enum(cls, 'Dynamically Assigned Socket Numbers [0x%s]' % hex(value)[2:].upper().zfill(4), value)
              return cls(value)
          if 0x8000 <= value <= 0xFFFF:
              extend_enum(cls, 'Statically Assigned Socket Numbers [0x%s]' % hex(value)[2:].upper().zfill(4), value)
              return cls(value)
          super()._missing_(value)
docs: Lookup function used when value is not found.