The example function_test.rb does not work.  First, the example calls #dump with no arguments.  However, the function
expects one argument, which appears to be the filename.  There were some comments in the source file about that not
working, but it seems to work.  In any case, the dump funtion requires one argument, or the test script fails.

Second, if the argument is added for dump, the test script gets to the #graph call, and fails saying "undefined
method 'graph'".  The source code defines #graph as a singleton method.  Changing the graph function definition
in the source code to a regular instance method rather than a singleton method appears to fix the problem.  I have to
admit I do not understand the significance of this being a singleton method, but in any case, unless this is done, the
example script fails.