Allow calling sequential() a bit longer, because CRAN package 'fiery' does it

Author: HenrikBengtsson

R/backend_api-SequentialFutureBackend-class.R

@@ -27,7 +27,10 @@
 #' @aliases uniprocess
 #' @export
 sequential <- function(..., envir = parent.frame()) {
-  stop("INTERNAL ERROR: The future::sequential() function implements the FutureBackend and should never be called directly")
+  .Deprecated("The future::sequential() function implements the FutureBackend and should never be called directly. This will soon become defunct")
+  f <- Future(..., envir = envir)
+  class(f) <- c("SequentialFuture", "UniprocessFuture", "Future")
+  f  
 }
 class(sequential) <- c("sequential", "uniprocess", "future", "function")