# File lib/core/facets/dir/lookup.rb, line 9
  def self.lookup(rel_path, parent_path='.')
    while true
      path = File.expand_path(rel_path, parent_path)

      return path if File.exists?(path)
      return nil if path == '/'

      parent_path = File.expand_path('..', parent_path)
    end
  end