rlangQQ_toTree <- function(e)
    if (is.symbol(e)) paste('Node', show2(e), '[]') else {


        paste('Node',
              show2(e[[1]]),
              if (length(e) < 2) '[]' else
                paste('[', paste(sapply(2:length(e), function(i) rlangQQ_toTree(e[[i]])), collapse=', '), ']') )
    }