code: def _new_Index(cls, d):
      
      # required for backward compat, because PI can't be instantiated with
      # ordinals through __new__ GH #13277
      if issubclass(cls, ABCPeriodIndex):
          from pandas.core.indexes.period import _new_PeriodIndex
          return _new_PeriodIndex(cls, **d)
      return cls.__new__(cls, **d)
docs: This is called upon unpickling, rather than the default which doesn't
      have arguments and breaks __new__.