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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _setup(self):
 """ 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. """

        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)