Simplify Unix Path2
Simplify a give path
Input: String. Unix path.
Output: String. Unix path.
Example:
simplify_path('/a/') == '/a'
simplify_path('/a/b') == '/a/b'
simplify_path('/a//b/c') == '/a/b/c'
simplify_path('/a/b/./ci') == '/a/b/ci'
simplify_path('/a/b/../c') == '/a/c'
