that corresponds to Expat xml attribute list @a atts.
 *
 * The hash's keys and values are <tt>char *</tt>'s.
 *
 * @a atts may be NULL, in which case you just get an empty hash back
 * (this makes life more convenient for some callers).
 */
apr_hash_t *
svn_xml_make_att_hash(const char **atts,
                      apr_pool_t *pool);


/** Like svn_xml_make_att_hash(), but takes a hash and preserves any
 * key/value pairs already in it.
 */
void
svn_xml_hash_atts_preserving(const char **atts,
                             apr_hash_t *ht,
                             apr_pool_t *pool);

/** Like svn_xml_make_att_hash(), but takes a hash and overwrites
 * key/value pairs already in it that also appear in @a atts.
 */
void
svn_xml_hash_atts_overlaying(const char **atts,
                             apr_hash_t *ht,
                             apr_pool_t *pool);