In the C++ programming language, one can do file I/O via so-called streams. In the operation ostream < < 42 < < "universe", ostream is an output stream, and < < is a binary infix operator that creates a new ostream (and outputs its right argument as a side effect). That is, ostream < < 42 is another ostream that can again be used for file I/O, e.g. using another instance of