code: def render(raw_config, environment=None):
      
  
      t = Template(raw_config)
      buff = StringIO()
      if not environment:
          environment = {}
      try:
          substituted = t.substitute(environment)
      except KeyError as e:
          raise exceptions.MissingEnvironment(e.args[0])
      except ValueError:
          # Support "invalid" placeholders for lookup placeholders.
          substituted = t.safe_substitute(environment)
  
      if not isinstance(substituted, str):
          substituted = substituted.decode('utf-8')
  
      buff.write(substituted)
      buff.seek(0)
      return buff.read()
docs: Renders a config, using it as a template with the environment.
  
      Args:
          raw_config (str): the raw stacker configuration string.
          environment (dict, optional): any environment values that should be
              passed to the config
  
      Returns:
          str: the stacker configuration populated with any values passed from
              the environment