def _apply_loffset(grouper, result):
    """
    (copied from pandas)
    if loffset is set, offset the result index

    This is NOT an idempotent routine, it will be applied
    exactly once to the result.

    Parameters
    ----------
    result : Series or DataFrame
        the result of resample
    """

    needs_offset = (
        isinstance(grouper.loffset, (pd.DateOffset, datetime.timedelta))
        and isinstance(result.index, pd.DatetimeIndex)
        and len(result.index) > 0
    )

    if needs_offset:
        result.index = result.index + grouper.loffset

    grouper.loffset = None