I am interested in adding multiple row annotations to my heatmap using the pheatmap function in R (example: https://stackoverflow.com/questions/41628450/r-pheatmap-change-annotation-colors-and-prevent-graphics-window-from-popping-up). The examples I see online all give only one annotation. What is the easy way to extend it to multiple row annotations?

from the pheatmap help:

```
# make test matrix
test = matrix(rnorm(200), 20, 10)
test[1:10, seq(1, 10, 2)] = test[1:10, seq(1, 10, 2)] + 3
test[11:20, seq(2, 10, 2)] = test[11:20, seq(2, 10, 2)] + 2
test[15:20, seq(2, 10, 2)] = test[15:20, seq(2, 10, 2)] + 4
colnames(test) = paste("Test", 1:10, sep = "")
rownames(test) = paste("Gene", 1:20, sep = "")

# define the annotation
annotation_row = data.frame(
                    GeneClass = factor(rep(c("Path1", "Path2", "Path3"), c(10, 4, 6))),
                  AdditionalAnnotation = c(rep("random1", 10), rep("random2", 10))
                )
rownames(annotation_row) = paste("Gene", 1:20, sep = "")

pheatmap(test, annotation_row = annotation_row)
```