# File lib/systemu.rb, line 229
  def slug_for(*args)
    options = args.last.is_a?(Hash) ? args.pop : {}
    join = (options[:join] || options['join'] || '_').to_s
    string = args.flatten.compact.join(join)
    words = string.to_s.scan(%r|[/\w]+|)
    words.map!{|word| word.gsub %r|[^/0-9a-zA-Z_-]|, ''}
    words.delete_if{|word| word.nil? or word.strip.empty?}
    words.join(join).downcase.gsub('/', (join * 2))
  end