program--

#' @title Build GBM Tree
#' @description Create a `data.tree` object from a GBM tree.
#' @param gbm_model Object of class `gbm`
#' @param i.tree Tree iteration to build from
#' @return A `data.tree` object from the `i.tree` tree of `gbm_model`.
build_tree <- function(gbm_model, i.tree = 1) {
    gbm_tree <- gbm::pretty.gbm.tree(gbm_model, i.tree = i.tree)
    pathString <- c("0" = "0")

    for (node in seq(1, nrow(gbm_tree) - 1)) {