options(width = 120)
library('data.tree')
library(yaml)
osList <- yaml.load_file("users.yaml")
osNode <- as.Node(osList)
osNode$Do(function(node) node$cumUser <- Cumulate(node,attribute = "users",aggFun = sum))
#birds$species <- function(self) sum(sapply(self$children, function(x) x$species))
print(osNode)