o o 2 7 +-+-+ +--+--+
| | | | |
10 11 13 14 15
-
-DEPTH can be a positive integer, 0, nil, or 'up. A positive
+DEPTH can be a positive integer, 0, nil, or \\='up. A positive
integer or 0 means go DEPTH deep counting from NODE. A nil means
-no limit. And a symbol 'up means go upwards only: only traverse
+no limit. And a symbol \\='up means go upwards only: only traverse
sibling and parent, never go down to children.
-The difference between 0 and 'up is subtle: in the above example,
+The difference between 0 and \\='up is subtle: in the above example,
if given 0 as DEPTH, node 1 3 4 5 6 8 9 12 16 are visited; if
-given 'up as DEPTH, only node 1 3 4 8 16 are visited."
+given \\='up as DEPTH, only node 1 3 4 8 16 are visited."
;; First try NODE's subtree, but only under these conditions: if
;; DEPTH is a number, it has to be greater than 0, if it's a symbol,
;; it cannot be 'up.