I guess this is encapsulates an invertible function, and the untranslate method is the inverse operation to translate.

It is assumed that untranslate(translate(x)) = x for all x in the source alphabet, and that translate(untranslate(y)) = y for all y in the target alphabet. Note, one interesting sub-set of reversible transforms are of the form translate(x) = untranslate(x), and represent 'mirror image' transformations.

Original BioJava version by Matthew Pocock. Port to C# by Doug Swisher.