#' @importFrom grDevices colors gray.colors
-#' @importFrom graphics abline hist par plot
+#' @importFrom graphics abline hist par plot matplot
#' @importFrom methods hasArg is
-#' @importFrom stats quantile sd
+#' @importFrom stats quantile sd cov
#' @importFrom utils getFromNamespace read.csv head tail
#' @importFrom R6 R6Class
#'