Example code for basic Call and Prepare/Flush.

Example functions for a simple Put & Get using Call(), and then for
Prepare() & Flush().

Each example is self-contained, and includes the server
setup/teardown.  This makes the code closer to what would be used in
an actual client program.

The Prepare() & Flush() is a bit long because we have to create the values
we are later scanning for.
You might just scan one half the expected range with the first scan and one half with the second. Idea here is to show that prepare/flush works for queries as well as updates.