def normalize_element(path)
      path = Pathname.new(path)
      path = @root.join(path) if path.relative?
      path.expand_path.to_s
    end
def normalize_element(path)
      path = Pathname.new(path)
      path = @root.join(path) if path.relative?
      path.expand_path.to_s
    end
Relative paths added to this array are expanded relative to `@root`.

     paths = Paths.new("/usr/local")
     paths << "tmp"
     paths << "/tmp"

     paths
     # => ["/usr/local/tmp", "/tmp"]