<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_bucket_region(self, bucket_name):
 """ Get region based on the bucket name. :param bucket_name: Bucket name for which region will be fetched. :return: Region of bucket name. """


        # Region set in constructor, return right here.
        if self._region:
            return self._region

        # get bucket location for Amazon S3.
        region = 'us-east-1'  # default to US standard.
        if bucket_name in self._region_map:
            region = self._region_map[bucket_name]
        else:
            region = self._get_bucket_location(bucket_name)
            self._region_map[bucket_name] = region

        # Success.
        return region