pub fn day_matches(
  plan: normalize.RRulePlan,
  date: ast.Date,
) -> Bool

pub fn first_time_on_day(
  plan: normalize.RRulePlan,
  date: ast.Date,
) -> ast.DateTime

pub fn matches(
  plan plan: normalize.RRulePlan,
  at at: ast.DateTime,
) -> Bool

pub fn next_occurrence(
  plan: normalize.RRulePlan,
  search search: ast.DateTime,
  guard guard: Int,
) -> option.Option(ast.DateTime)

pub fn next_time_on_day(
  plan: normalize.RRulePlan,
  date: ast.Date,
  search: ast.DateTime,
) -> option.Option(ast.DateTime)

pub fn yielded_before(
  plan plan: normalize.RRulePlan,
  cursor cursor: ast.DateTime,
) -> Int