@type t() :: %Cldr.Calendar.Config{
  begins_or_ends: :begins | :ends,
  calendar: atom(),
  cldr_backend: Cldr.backend() | nil,
  cldr_calendar_type: :gregorian | :japanese,
  day_of_week: Cldr.Calendar.day_of_week(),
  first_or_last: :first | :last,
  min_days_in_first_week: 1..7,
  month_of_year: pos_integer(),
  weeks_in_month: [pos_integer()],
  year: :majority | :starts | :ends
}