#'
#' @field data List of
#' \itemize{
#' \item time: vector of times
#' \item serie: centered series
#' \item level: corresponding levels
#'
#' @field data List of
#' \itemize{
#' \item time: vector of times
#' \item serie: centered series
#' \item level: corresponding levels
},
append = function(new_time, new_serie, new_level, new_exo_hat, new_exo)
{
},
append = function(new_time, new_serie, new_level, new_exo_hat, new_exo)
{