instance method variant=

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 70
      def variant=(variant)
        if variant.is_a?(Symbol)
          @variant = [variant]
        elsif variant.nil? || variant.is_a?(Array) && variant.any? && variant.all?{ |v| v.is_a?(Symbol) }
          @variant = variant
        else
          raise ArgumentError, "request.variant must be set to a Symbol or an Array of Symbols, not a #{variant.class}. " \
            "For security reasons, never directly set the variant to a user-provided value, " \
            "like params[:variant].to_sym. Check user-provided value against a whitelist first, " \
            "then set the variant: request.variant = :tablet if params[:variant] == 'tablet'"
        end
      end