The class "crystal.list" has methods for the following generic functions:
$, $<-, [, [<-, [[, [[<-, as.matrix, boxplot, dotchart, pcosts, plot, print,
shrink, stack.plot, summary, eda.plot.
as.crystal.list coerces a crystal.vector object to a crystal.list object.
as.vector.crystal.list coerces a crystal.list object to a vector.