def underscore(camel_cased_word)
      word = camel_cased_word.to_s.dup
      word.gsub!('::', '/')
      word.gsub!(/(?:([A-Za-z\d])|^)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1}#{$1 && '_'}#{$2.downcase}" }
      word.gsub!(/([A-Z\d]+)([A-Z][a-z])/,'\1_\2')
      word.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
      word.tr!("-", "_")
      word.downcase!
      word
    end
def underscore(camel_cased_word)
      word = camel_cased_word.to_s.dup
      word.gsub!('::', '/')
      word.gsub!(/(?:([A-Za-z\d])|^)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1}#{$1 && '_'}#{$2.downcase}" }
      word.gsub!(/([A-Z\d]+)([A-Z][a-z])/,'\1_\2')
      word.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
      word.tr!("-", "_")
      word.downcase!
      word
    end
Makes an underscored, lowercase form from the expression in the string.

 Changes '::' to '/' to convert namespaces to paths.

   "ActiveModel".underscore         # => "active_model"
   "ActiveModel::Errors".underscore # => "active_model/errors"

 As a rule of thumb you can think of +underscore+ as the inverse of +camelize+,
 though there are cases where that does not hold:

   "SSLError".underscore.camelize # => "SslError"