TreePosition

TreePosition[tree,pattern] gives a list of the positions of subtrees of tree whose data matches pattern.

TreePosition[tree,pattern,levelspec] finds only matches that appear on levels of tree specified by levelspec.

TreePosition[tree,pattern,levelspec,n] gives the positions of the first n matches found.

TreePosition[pattern] represents an operator form of TreePosition that can be applied to a tree.

Examples

Find positions of nodes with data matching a pattern:

t = Tree[a, {Tree[b, {Tree[c, None], Tree[d, None]}], Tree[e, None]}];
TreePosition[t, b]
(* {{1}} *)

Please visit the official Wolfram Language Reference for more details.