removed at_end arg as we were not using it and likely will not eith…

…er in future (discussed in #216)

R/misc.R

@@ -33,11 +33,8 @@ names0 <- function(num, prefix = "x") {
   paste0(prefix, ind)
 }
 
-add_class <- function(x, cls, at_end = FALSE) {
-  class(x) <- if (at_end)
-    c(class(x), cls)
-  else
-    c(cls, class(x))
+add_class <- function(x, cls) {
+  class(x) <- c(cls, class(x))
   x
 }