#' Flat prediction: always forecast a serie of zeros.
#' This serie is then adjusted using the ".pjump" function (see \code{Forecaster} class).
#'
-#' @usage ZeroForecaster$new(pjump)
+#' @usage # ZeroForecaster$new(pjump)
#'
#' @docType class
#' @format R6 class, inherits Forecaster