instance method verification_strategy

# File actionpack/lib/action_controller/metal/request_forgery_protection.rb, line 356
        def verification_strategy(name)
          case name
          when :header_only, :header_or_legacy_token
            name
          else
            raise ArgumentError, "Invalid request forgery verification strategy, use :header_only or :header_or_legacy_token."
          end
        end