Simplify Unix Path

**English**

You can think about it as simplifying of the first argument "cd" command (a standart bash command). Simplifying means making shorter.

For instance if I do `cd a/../b`

it works the same as `cd b`

. Which means "b" is simplifying of "a/../b". It is much easier to explain everything using examples.

**Input: ** String. Non-Empty valid unix path.

**Output: ** String. Unix path.

**Example:**

# last slash is not important simplify_path('/a/') == '/a' # double slash can be united in one simplify_path('/a//b/c') == '/a/b/c' # double dot - go to previous folder simplify_path('dir/fol/../no') == 'dir/no' simplify_path('dir/fol/../../no') == 'no' # one dot means current dir simplify_path('/a/b/./ci') == '/a/b/ci' simplify_path('vi/..') == '.' simplify_path('./.') == '.' # you can't go deeper than root folder simplify_path('/for/../..') == '/' simplify_path('/for/../../no/..') == '/' # not all double-dots can be simplyfied in related path simplify_path('for/../..') == '..' simplify_path('../foo') == '../foo'