- (handle-not-found [proc]) parameter
The handler for nonexistent files. If the requested URL does not point to an existing file or directory, this procedure is called. It is a procedure of one argument, the path (a string) to the first missing file in the request path. This path should be interpreted as being relative to the webroot (even though it points to no existing file). Defaults to a procedure which returns a "404 Not found".