underscore

# File activesupport/lib/active_support/inflector.rb, line 124
  def underscore(camel_cased_word)
    camel_cased_word.to_s.gsub(/::/, '/').
      gsub(/([A-Z]+)([A-Z][a-z])/,'\1_\2').
      gsub(/([a-z\d])([A-Z])/,'\1_\2').
      tr("-", "_").
      downcase
  end