code: def _setup(self):
          
          context_module = os.environ.get(ENVIRONMENT_CONTEXT_VARIABLE, 'context')
          if not context_module:
              raise ImproperlyConfigured(
                  'Requested context points to an empty variable. '
                  'You must either define the environment variable {0} '
                  'or call context.configure() before accessing the context.'
                  .format(ENVIRONMENT_CONTEXT_VARIABLE))
  
          self._wrapped = Settings(context_module, default_settings=global_context)
docs: Load the context module pointed to by the environment variable. This
          is used the first time we need the context at all, if the user has not
          previously configured the context manually.