@spec china_now() :: {:ok, DateTime.t()}

@spec china_today() :: Date.t()

@spec date_to_datetime(Date.t(), binary()) :: DateTime.t()

@spec datetime_to_naive(DateTime.t()) :: NaiveDateTime.t()

@spec datetime_to_str(DateTime.t(), String.t()) :: String.t()

@spec datetime_to_ts(DateTime.t()) :: integer()

@spec naive_now(atom()) :: NaiveDateTime.t()

@spec naive_to_datetime(NaiveDateTime.t(), Calendar.time_zone()) ::
  {:ok, DateTime.t()}

@spec naive_to_datetime!(NaiveDateTime.t(), Calendar.time_zone()) :: DateTime.t()

@spec now(Calendar.time_zone()) :: {:ok, DateTime.t()}

@spec now!(Calendar.time_zone()) :: DateTime.t()

@spec str_to_datetime(String.t(), String.t()) :: {:ok, DateTime.t()}

@spec timestamp(atom()) :: integer()

@spec ts_to_datetime(integer(), Calendar.time_zone()) :: {:ok, DateTime.t()}