This program is conceptually very similar to hello.chpl, but it uses a more structured programming style,
explicitly defining a module, a configuration constant, and a
main() procedure.

The following statement declares a module named 'Hello'. If a
source file contains no module declarations, the filename minus its
.chpl extension serves as the module name for the code it
contains. Thus, 'hello' would be the automatic module name for the
previous hello.chpl example.

moduleHello{

This next statement declares a configuration constant named
message. The type is inferred to be a string since the
initializing expression is a string literal. Users may override
the default values of configuration constants and variables on the
executable's command-line. For example, we could change the
default message for a given run using the command line: ./hello--message="hiya!".

configconstmessage="Hello, world!";

Any top-level code in a module is executed as part of the module's
initialization when the program begins executing. Thus, in the
previous one-line hello.chpl, the presence
of a writeln() at the file scope formed the implicit hello
module's initialization and would be executed at program startup.
Since there was no explicit main() function or any other
top-level code, that's all that the program would do.

In this program, we define an entry point for the program by
defining a procedure named main(). This will be invoked after
this module and all the modules it uses are initialized.