ActiveRecord::LegacyYamlAdapter

# File activerecord/lib/active_record/legacy_yaml_adapter.rb, line 5
    def self.convert(klass, coder)
      return coder unless coder.is_a?(Psych::Coder)

      case coder["active_record_yaml_version"]
      when 1, 2 then coder
      else
        if coder["attributes"].is_a?(ActiveModel::AttributeSet)
          Rails420.convert(klass, coder)
        else
          Rails41.convert(klass, coder)
        end
      end
    end