ewoc-nth
ewoc-nth is a compiled Lisp function in `ewoc.el
'.
(ewoc-nth EWOC N)
Return the Nth node.
N counts from zero. Return nil if there is less than N elements.
If N is negative, return the -(N+1)th last element.
Thus, (ewoc-nth ewoc 0) returns the first node,
and (ewoc-nth ewoc -1) returns the last node.
Use `ewoc-data' to extract the data from the node.