def get_shifted_holidays(self, dates):
for holiday, label in dates:<EOL><INDENT>if holiday.weekday() == SUN:<EOL><INDENT>yield (<EOL>holiday + timedelta(days=<NUM_LIT:1>),<EOL>label + '<STR_LIT>'<EOL>)<EOL><DEDENT><DEDENT>
Taking a list of existing holidays, yield a list of 'shifted' days if
the holiday falls on SUN.