Why ls() changes current working dir (cwd)?

[ksmolyanin]

I think your library is excellent but ...
I guess that semantics of ls() (derived from UNIX "ls" command) presupposes its read only behavior. In your implementation it changes current working directory. For example these steps:
mkdir('/dir1' ....
ls('/dir1/' ...
mkdir('/dir2' ...
lead to the following dir structure:
/dir1/dir2
(dir2 is a sub-folder)
while these ones (just without intermediate ls()):
mkdir('/dir1' ....
mkdir('/dir2' ...
to this structure:
/dir1
/dir2
(both dirs are in the root)

[ebidel]

Can't remember why I did this, but I'll look into it. #20 is related.