def reset_attribute!(name)
      value = attribute_was(name)
      if value
        @attributes[name] = value
        modifications.delete(name)
      end
    end
def reset_attribute!(name)
      value = attribute_was(name)
      if value
        @attributes[name] = value
        modifications.delete(name)
      end
    end
Resets a changed field back to its old value.

 Example:

   person = Person.new(:title => "Sir")
   person.title = "Madam"
   person.reset_attribute!("title")
   person.title # "Sir"

 Returns:

 The old field value.