<B>Padre::Task::EvalB> is a stub class used to implement testing and other
It takes three named string parameters matching each of the three execution
phases. When each phase of the task is run, the string will be evaled and
the result will be stored in the same has key as the source string.
If the key does not exist at all, nothing will be executed for that phase.
Regardless of the execution result (or the non-execution of the phase) each
phase will always return true. However, if the string eval throws an
exception it will escape the task object (although when run properly inside
of a task handle it should be caught by the handle).