code: def environ_setting(name, default=None, required=True):
      
      if name not in os.environ and default is None:
          message = "The {0} ENVVAR is not set.".format(name)
          if required:
              raise ImproperlyConfigured(message)
          else:
              warnings.warn(ConfigurationMissing(message))
  
      return os.environ.get(name, default)
docs: Fetch setting from the environment. The bahavior of the setting if it
      is not in environment is as follows:
  
          1. If it is required and the default is None, raise Exception
          2. If it is requried and a default exists, return default
          3. If it is not required and default is None, return  None
          4. If it is not required and default exists, return default