> m <- matrix(c("blue", "yellow"), nrow = 2L, ncol = 2L)
> r <- as.raster(m)
> rt <- bm_extend(r, value = "red", top = 1L)
> print(inherits(rt, "raster"))
[1] TRUE

> bm_print(rt)
[31m█[39m[31m█[39m
[34m█[39m[34m█[39m
[33m█[39m[33m█[39m

> rr <- bm_extend(r, value = "red", right = 1L)
> bm_print(rr)
[34m█[39m[34m█[39m[31m█[39m
[33m█[39m[33m█[39m[31m█[39m

> rb <- bm_extend(r, value = "red", bottom = 1L)
> bm_print(rb)
[34m█[39m[34m█[39m
[33m█[39m[33m█[39m
[31m█[39m[31m█[39m

> rl <- bm_extend(r, value = "red", left = 1L)
> bm_print(rl)
[31m█[39m[34m█[39m[34m█[39m
[31m█[39m[33m█[39m[33m█[39m

