    # File lib/active_support/inflector.rb, line 54
        def irregular(singular, plural)
          if singular[0,1].upcase == plural[0,1].upcase
            plural(Regexp.new("(#{singular[0,1]})#{singular[1..-1]}$", "i"), '\1' + plural[1..-1])
            singular(Regexp.new("(#{plural[0,1]})#{plural[1..-1]}$", "i"), '\1' + singular[1..-1])
          else
            plural(Regexp.new("#{singular[0,1].upcase}(?i)#{singular[1..-1]}$"), plural[0,1].upcase + plural[1..-1])
            plural(Regexp.new("#{singular[0,1].downcase}(?i)#{singular[1..-1]}$"), plural[0,1].downcase + plural[1..-1])
            singular(Regexp.new("#{plural[0,1].upcase}(?i)#{plural[1..-1]}$"), singular[0,1].upcase + singular[1..-1])
            singular(Regexp.new("#{plural[0,1].downcase}(?i)#{plural[1..-1]}$"), singular[0,1].downcase + singular[1..-1])
          end
        end