code: def period_index(entry: DataEntry, freq=None) -> pd.PeriodIndex:
      if freq is None:
          freq = entry[FieldName.START].freq
  
      return pd.period_range(
          start=entry[FieldName.START],
          periods=entry[FieldName.TARGET].shape[-1],
          freq=freq,
      )
  
imports: from typing import Optional
  import pandas
  from .common import DataEntry
  from .field_names import FieldName
label_desc: Use image node_id 2 for calling a global function with example usage: period_index(entry, freq) and returns: pd