code: def initialize(template, service_name, environment='dev'):
      
      template.SERVICE_NAME = os.getenv('SERVICE_NAME', service_name)
      template.SERVICE_ENVIRONMENT = os.getenv('ENV', environment).lower()
      template.DEFAULT_TAGS = troposphere.Tags(**{
          'service-name': template.SERVICE_NAME,
          'environment': template.SERVICE_ENVIRONMENT
      })
      template.add_version("2010-09-09")
      template.add_description("Stack for %s microservice" % service_name)
docs: Adds SERVICE_NAME, SERVICE_ENVIRONMENT, and DEFAULT_TAGS to the template
  
      :param template:
      :param service_name:
      :param environment:
      :return: