func get_root_children works

tree.go

@@ -32,6 +32,22 @@ func get_children(header_index int, headings []heading) []heading {
 	return children
 }
 
+func get_root_children(headings []heading) []int {
+	var root_children []int
+
+	lowest_level := 0
+	for index, value := range headings {
+		cur_level := value.level
+		if index == 0 || cur_level <= lowest_level {
+			root_children = append(root_children, index)
+			lowest_level = cur_level
+		}
+	}
+
+	return root_children
+}
+
+// TODO: -1 for root -> get indices for headers lying directly under root
 func get_child_indices(header_index int, headings []heading) []int {
 	var children []int