[lifthrasiir]

In my opinion the most interesting aspect of iostream is the ability to inject a state to the stream: xalloc, iword and pword; they are required to make your own manipulators like `hex` or `setw`. Of course, this is to support a (questionable, again in my opinion) design of manipulators conceptually affecting the state of stream, and there are many saner alternative designs not requiring this kind of "extensibility".