def _reference_dates(self, start_date, end_date):
if self.start_date is not None:<EOL><INDENT>start_date = self.start_date.tz_localize(start_date.tz)<EOL><DEDENT>if self.end_date is not None:<EOL><INDENT>end_date = self.end_date.tz_localize(start_date.tz)<EOL><DEDENT>year_offset = DateOffset(years=<NUM_LIT:1>)<EOL>reference_start_date = Timestamp(<EOL>datetime(start_date.year - <NUM_LIT:1>, self.month, self.day))<EOL>reference_end_date = Timestamp(<EOL>datetime(end_date.year + <NUM_LIT:1>, self.month, self.day))<EOL>dates = date_range(start=reference_start_date,<EOL>end=reference_end_date,<EOL>freq=year_offset, tz=start_date.tz)<EOL>return dates<EOL>
Get reference dates for the holiday.

Return reference dates for the holiday also returning the year
prior to the start_date and year following the end_date.  This ensures
that any offsets to be applied will yield the holidays within
the passed in dates.