Function parent_dir 

pub fn parent_dir(rel: &str) -> String

The immediate parent directory of a relative path ("." for a root-level file). Used to group files for the per-folder predicate and --summary dir.

Examples

use coding_tools::tree::parent_dir;

assert_eq!(parent_dir("a/b/c.rs"), "a/b");
assert_eq!(parent_dir("top.rs"), ".");