Superclass of things that can be printed in the resulting circuit
Usually created using the custom string interpolator p"..."
TODO Add support for names of Modules
Currently impossible because unpack is called before the name is selected
Could be implemented by adding a new format specifier to Firrtl (eg. %m)
TODO Should we provide more functions like map and mkPrintable?
Unpack into format String and a List of String arguments (identifiers)
This must be called after elaboration when Chisel nodes actually
Allow for appending Strings to Printables
Allow for appending Printables like Strings