Implementing this interface allows a Program to have a description
of the plan which can be shown to the user. For a more detailed description
of what should be included in the description see getDescription().
Returns a description of the plan that is generated by the assembler and
also of the arguments if they are available. The description should be simple
text as it may be rendered in different environments (console, web interface, ...).
Typical things that should be included are:
expected input format
description of output
description of what is done
description of arguments to customize plan if available
A description of the program and of its arguments if available.