NULL_LEFT_CHILD   545 src/intervals.c   if (NULL_LEFT_CHILD (interval))
NULL_LEFT_CHILD   666 src/intervals.c       while (! NULL_LEFT_CHILD (i))
NULL_LEFT_CHILD   700 src/intervals.c   if (! NULL_LEFT_CHILD (interval))
NULL_LEFT_CHILD  1392 src/intervals.c       while (! NULL_LEFT_CHILD (successor))
NULL_LEFT_CHILD  1444 src/intervals.c   if (! NULL_LEFT_CHILD (i))	/* It's below us. Go down,
NULL_LEFT_CHILD  1500 src/intervals.c   if (! NULL_LEFT_CHILD (source))