## Description:

Calendar enumeration and math

Enumerates through a calendar and performs calendar math.

Calendars use local time zone information, which includes periodic adjustments for things like Daylight Saving Time and leap years. Enumerating where necessary helps avoid making assumptions about the duration of various calendar periods.

Calendar math may produce different results depending on the local time of the system. Code which uses the Calendar class should therefore be tested across different time zones and date spans over which it might be used.