I'm building my own HolidayCalendar.
I want some Saturdays to be business days.
But Mathematica considers every Saturday a holiday, even for my HolidayCalendar.
For instance,
DayRange[DateObject[{2020,1,1}], DateObject[{2020,1,31}], "BusinessDay", HolidayCalendar -> { "Gregorian" -> {{True&, #==1&, #==1&}}}] gives me no Saturdays and no Sundays, of course.
Is it possible to change this behavior?
