# File lib/fog/aws/requests/compute/modify_image_attribute.rb, line 43
        def modify_image_attribute(image_id, attributes)
          raise ArgumentError.new("image_id is required") unless image_id

          unless self.data[:images][image_id]
            raise Fog::Compute::AWS::NotFound.new("The AMI ID '#{image_id}' does not exist")
          end

          (attributes['Add.UserId'] || []).each do |user_id|
            if image_launch_permissions = self.data[:image_launch_permissions][image_id]
              image_launch_permissions[:users].push(user_id)
            end
          end

          (attributes['Remove.UserId'] || []).each do |user_id|
            if image_launch_permissions = self.data[:image_launch_permissions][image_id]
              image_launch_permissions[:users].delete(user_id)
            end
          end

          response = Excon::Response.new
          response.status = 200
          response.body = {
            'return'        => true,
            'requestId'     => Fog::AWS::Mock.request_id
          }
          response
        end