def occurrence(self, indicator=None):
        """Update the URI to retrieve file occurrences for the provided indicator.

        Args:
            indicator (string): The indicator to retrieve file occurrences.
        """
        self._request_entity = 'fileOccurrence'
        self._request_uri = '{}/fileOccurrences'.format(self._request_uri)
        if indicator is not None:
            self._request_uri = '{}/{}/fileOccurrences'.format(self._api_uri, indicator)
Update the URI to retrieve file occurrences for the provided indicator.

        Args:
            indicator (string): The indicator to retrieve file occurrences.