#' Coerce to a Data Frame
#'
#' Functions to check if an object is a data frame, or coerce it if possible.
#'
#' @param x Any R object.
#' @param ... Additional arguments to be passed to or from methods.
#'
#'
#' @method as.data.frame density
#' @export
as.data.frame.density <- function(x, ...) {
  data.frame(x = x$x, y = x$y)
}