diff --git a/R/ggkegg.R b/R/ggkegg.R
index dbaec05..821bcaa 100644
--- a/R/ggkegg.R
+++ b/R/ggkegg.R
@@ -34,7 +34,7 @@
 #' @param numeric_attribute named vector for appending numeric attribute
 #' @param node_rect_nudge parameter for nudging the node rect
 #' @param group_rect_nudge parameter for nudging the group node rect
-#' @example
+#' @examples
 #' ## Use pathway ID to obtain `ggraph` object directly.
 #' g <- ggkegg("hsa04110")
 #' g + geom_node_rect()
diff --git a/R/module_functions.R b/R/module_functions.R
index 526cd6c..3bb004c 100644
--- a/R/module_functions.R
+++ b/R/module_functions.R
@@ -722,7 +722,7 @@ parse_module <- function(kmo) {
         }
         steps[[j]] <- current_step
         j <- j + 1
-        steps[sapply(steps, is.null)] <- NULL
+        steps[vapply(steps, is.null, FUN.VALUE=TRUE)] <- NULL
         return(steps)
     }
     ## Preallocate   
diff --git a/man/ggkegg.Rd b/man/ggkegg.Rd
index 1a6aa8f..059c896 100644
--- a/man/ggkegg.Rd
+++ b/man/ggkegg.Rd
@@ -75,3 +75,8 @@ ggplot2 object
 main function parsing KEGG pathway data,
 making igraph object and passing it to ggraph.
 }
+\examples{
+## Use pathway ID to obtain `ggraph` object directly.
+g <- ggkegg("hsa04110")
+g + geom_node_rect()
+}