compare_date(date1, date2, creation_year_int)

compare_day(day1, day2)
day1 and day2 are strings indicating day

compare_in_year()

compare_month(month1, month2)

compare_month_week_at_year_boundary(month_year, week_year, month, week, month_day, week_day)
compare month to week, parameters are all integers

compare_short_year(year1, year2)
year1 and year2 both are of string type

compare_week(week1, week2)
week1 and week2 are strings containing 'W' indicating the type is week.
Also suppose weeks do not contain 'X'

compare_week_month(month1, month2)

compare_week_month_aux(week, month, week_day, month_day)

compare_week_month_aux_aux(week_int, month_int, week_day_int, month_day_int)

compare_year(year1, year2, creation_year_int)
year1 and year2 both are of string type.
return: the link between two years

get_current_year()
input: none
output: integer

need_compare_at_year_boundary(year1, year2, month1, month2, day1, day2)

reverse_link(link)

simple_compare(time1, time2)
used only in month section

strip_week(week)

test_compare_date(test_string)

type_of_day(day)

type_of_month(month)
types include: "MONTH", "WEEK", "SEASON", "VAGUE"

type_of_year(year)

year_alpha_to_digit(year, creation_year_int)