OrderedRunner takes an array of objects of type RunningFunction and tells each to run in sequence, quitting if there are any errors.

@TODO - create different pretty printers without the runner command.

BoolFunction implements RunningFunction interface, and supports Functions with a single bool argument.

StringFunction implements RunningFunction interface, and supports Functions with a single string argument.

StringSliceFunction implements RunningFunction interface, and supports Functions with a single string argument.

VoidFunction implements RunningFunction interface, and supports Functions with no arguments.

RunningFunction defines a generic interface to run functions.