> m <- matrix(c("blue", "yellow"), nrow = 2L, ncol = 2L)
> pm <- as_bm_pixmap.matrix(m)
> print(bm_extend(pm, value = "red", top = 1L))
[31m█[39m[31m█[39m
[33m█[39m[33m█[39m
[34m█[39m[34m█[39m

> print(bm_extend(pm, value = "red", right = 1L))
[33m█[39m[33m█[39m[31m█[39m
[34m█[39m[34m█[39m[31m█[39m

> print(bm_extend(pm, value = "red", bottom = 1L))
[33m█[39m[33m█[39m
[34m█[39m[34m█[39m
[31m█[39m[31m█[39m

> print(bm_extend(pm, value = "red", left = 1L))
[31m█[39m[33m█[39m[33m█[39m
[31m█[39m[34m█[39m[34m█[39m

