Updated Examples and Recipes (markdown)

Examples-and-Recipes.md

@@ -7,6 +7,7 @@ This page contains examples and recipes contributed by community members. Feel f
 - [Converting from {year, microseconds} to CCSDS](#ccsds)
 - [Difference in months between two dates](#deltamonths)
 - [Parsing ISO strings](http://stackoverflow.com/a/33438989/576911)
+- [2Gs Birthday](#birthday2gs)
 
 ***
 
@@ -244,6 +245,38 @@ This outputs:
 
 These are all reasonable answers to the question, and all easily computable with this library.
 
+<a name="birthday2gs"></a>
+### 2Gs Birthday
+(by [Howard Hinnant](https://github.com/HowardHinnant))
+
+This example demonstrates both some simple date arithmetic, and how to handle discontinuities in a timezone.  Dave was born in the "America/Los_Angeles" timezone at 10:03am on April 24, 1954.  When will he be 2,000,000,000 seconds old (in the same timezone?
+
+    #include <chrono>
+    #include <iostream>
+    #include "date.h"
+    #include "tz.h"
+ 
+    int
+    main()
+    {
+        using namespace std::chrono_literals;
+        using namespace date;
+        //  Dave was born April 24, 1954. 10:03 AM pst
+        //  Want to know when he is 2 Gigaseconds old
+        auto birth = day_point{apr/24/1954} + 10h + 3min;
+        auto z = locate_zone("America/Los_Angeles");
+        auto t = z->to_sys(birth);
+        t += 2'000'000'000s;
+        auto p = z->to_local(t);
+        std::cout << p.first << ' ' << p.second << '\n';
+    }
+
+One first creates the local time, and then converts that to UTC using the `Zone` for "America/Los_Angeles".  Then add 2Gs, then convert the time from UTC back to "America/Los_Angeles".  The result is a pair, with the first part holding a `time_point` and the second part holding the abbreviation for the local time.  This outputs:
+
+2017-09-08 14:36:20 PDT
+
+Note that without handling the timezone correctly, this result would be an hour off (2017-09-08 13:36:20) because the birth date falls in PST, and the celebration date falls in PDT.
+
 ***
 
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