from enum import Enum, EnumMeta

class MyMeta(EnumMeta):
  pass
class MyEnumBase1(Enum, metaclass=MyMeta):
  pass

# SUCCEEDS: MyEnum1
class MyEnum1(MyEnumBase1):
  one = 1
# SUCCEEDS: MyEnum4
MyEnum4 = Enum('MyEnum2', [], type=MyEnumBase1)
# FAILURE: MyEnum2 fails with KeyError.
MyEnum2 = Enum('MyEnum2', ['one'], type=MyEnumBase1)

# SUCCEEDS: MyEnum4
class MyEnumBase2(Enum, metaclass=EnumMeta):
  pass
MyEnum4 = Enum('MyEnum3', ['one'], type=MyEnumBase2)