code: def coerce_datetime_to_period_index(
      data: Optional[Union[pd.Series, pd.DataFrame, Any]],
      freq: Optional[str] = None,
      inplace: bool = False,
  ) -> Optional[Union[pd.Series, pd.DataFrame, Any]]:
      """Converts a dataframe or series index from DatetimeIndex to PeriodIndex
  
      Parameters
      ----------
      data : Optional[Union[pd.Series, pd.DataFrame, Any]]
          The data with a DatetimeIndex that needs to be converted to PeriodIndex
          If None, it does nothing.
      freq : Optional[str], optional
          The frequency to be used to convert the index, by default None which
          uses data.index.freq to perform the conversion
      inplace : bool, optional
          If True, convert inplace and do not return anything.
          If False, then do not modify the original object and return a copy with
          converted index, by default False
  
      Returns
      -------
      Optional[Union[pd.Series, pd.DataFrame, Any]]
          The data with PeriodIndex. Note: If input is not of type pd.Series or
          pd.DataFrame, then no change is made to the data.
      """
      if isinstance(data, (pd.DataFrame, pd.Series)):
          data_ = data.copy() if not inplace else data
  
          if isinstance(data_.index, pd.DatetimeIndex):
              if freq is None:
                  # Inferred by default
                  # Do not pass from freq=data_.index.freq. Let it infer by default
                  # since the data_ frequency could be MonthBegin which gives error
                  # if explicitly passed to `to_period`, but works ok if we allow
                  # it to infer automatically.
                  data_.index = data_.index.to_period()
              else:
                  data_.index = data_.index.to_period(freq=freq)
  
          if not inplace:
              return data_
  
      elif not inplace:
          return data
  
      return None
  
label_desc: Use image node_id 2 for calling a global function with example usage: coerce_datetime_to_period_index(data, freq, inplace) and returns: None, data_, data