File.parentDir

Returns the parent directory of the path.

The parent dir of the root directory is returned as null.

file'/dir1/dir2/file.txt'.parentDir()
//= dir'/dir1/dir2'

dir'/dirA/dirB/dirC'.parentDir()
//= dir'/dirA/dirB'

dir'/someDir'.parentDir()
//= dir'/'

dir'/'.parentDir()
//= null