    # File lib/fog/aws/requests/cloud_formation/update_stack.rb, line 28
            def update_stack(stack_name, options = {})
              params = {
                'StackName' => stack_name,
              }

              if options['Parameters']
                options['Parameters'].keys.each_with_index do |key, index|
                  index += 1 # params are 1-indexed
                  params.merge!({
                    "Parameters.member.#{index}.ParameterKey"   => key,
                    "Parameters.member.#{index}.ParameterValue" => options['Parameters'][key]
                  })
                end
              end

              if options['TemplateBody']
                params['TemplateBody'] = options['TemplateBody']
              elsif options['TemplateURL']
                params['TemplateURL'] = options['TemplateURL']
              end

              if options['Capabilities']
                params.merge!(Fog::AWS.indexed_param("Capabilities.member", [*options['Capabilities']]))
              end

              request({
                'Action'    => 'UpdateStack',
                :parser     => Fog::Parsers::AWS::CloudFormation::UpdateStack.new
              }.merge!(params))
            end