# File lib/buildr/core/project.rb, line 66
    def expand(*args)
      args = args.compact.reject { |s| s.to_s.empty? }.map(&:to_sym)
      return '' if args.empty?
      @mapping[args] ||= File.join(*[expand(*args[0..-2]), args.last.to_s].reject(&:empty?)) if args.size > 1
      return @mapping[args] || args.first.to_s
    end