Since there was a bit of confusion last time, I'll start by saying I am working on the subprocess.Popen module for Google Summer of Code. One of the features I am implementing is a class so that a running process can stand in in place of a file. For examples, instead of open( "filelist", mode = 'r') one would call ProcessIOWrapper( "ls -l", mode = 'r'). I am trying to decide if I should fully implement the mode argument. Right now, it essentially ignores everything but a 'U' indicated universal newlines in the mode argument. Should I leave that as is or make it so that things like "r+", "w", "a" are handled the way they would be for an actual file?