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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 get_key_name(self, environ, response_interception, exception=None):
 """Get the timer key name. :param environ: wsgi environment :type environ: dict :param response_interception: dictionary in form {'status': '<response status>', 'response_headers': [<response headers], 'exc_info': <exc_info>} This is the interception of what was passed to start_response handler. :type response_interception: dict :param exception: optional exception happened during the iteration of the response :type exception: Exception :return: string in form '{{UNDERSCORED_PATH}}.{{METHOD}}.{{STATUS_CODE}}' :rtype: str """

        status = response_interception.get('status')
        status_code = status.split()[0]  # Leave only the status code.
        # PATH_INFO can be empty, so falling back to '/' in that case
        path = CHAR_RE.sub(self.separator, (environ['PATH_INFO'].rstrip('\/') or '/')[1:])
        parts = [path, environ['REQUEST_METHOD'], status_code]
        if exception:
            parts.append(exception.__class__.__name__)
        return '.'.join(parts)