bind: fn (source, target: string, flag: int): int;
## returns 0 if successful, -1 if unsuccessful.For bind, source is the name of an existing file or directory in the current namespace. After a successful bind call, the file name target is an alias for the object originally named by source. If the modification doesn't hide the original, source will still refer to the original file. The evaluation of source happens at the time of the bind, not when the binding is used.
sys->bind("#s","/chan",sys->MBEFORE); f2chanio := sys->file2chan("/chan", filename);