It seems rather questionable to assume that the average reader of that documentation would be equated with university level mathematical logic. In the case in question "Returns true iff the directory dir exists. If dir is a file, false is returned. Follows symlinks." where is the second parameter that is necessary in the suggested usage? Returns true if the directory exists and what other condition is evaluated? Apologies if it should be obvious but I genuinely don't see 2 conditions there.
Why the inconsistent naming might be a more exciting question: why not existsSymlink() ?
