docs: def get_next_environment(env):
      """
      Given an environment, return the next environment in the
      promotion hierarchy
      """
      config = _config_file()
  
      juicer.utils.Log.log_debug("Finding next environment...")
  
      if env not in config.sections():
          raise JuicerConfigError("%s is not a server configured in juicer.conf", env)
  
      section = dict(config.items(env))
  
      if 'promotes_to' not in section.keys():
          err = "Environment `%s` has no entry for `promotes_to`\nCheck man 5 juicer.conf." % env
          raise JuicerConfigError(err)
  
      return section['promotes_to']