# NOT RUN {
if (requireNamespace("mlr3pipelines", quietly = TRUE) &&
  requireNamespace("rpart", quietly = TRUE)) {
  library(mlr3)
  library(mlr3pipelines)
  set.seed(1)
  task = tsk("boston_housing")
  # Option 1: Use a learner that can predict se
  learn = lrn("regr.featureless", predict_type = "se")
  pred = learn$train(task)$predict(task)
  poc = po("compose_probregr")
  poc$predict(list(pred, pred))[[1]]
  # Option 2: Use two learners, one for response and the other for se
  learn_response = lrn("regr.rpart")
  learn_se = lrn("regr.featureless", predict_type = "se")
  pred_response = learn_response$train(task)$predict(task)
  pred_se = learn_se$train(task)$predict(task)
  poc = po("compose_probregr")
  poc$predict(list(pred_response, pred_se))[[1]]
}
# }
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