> m <- matrix(c("blue", "yellow"), nrow = 2L, ncol = 2L)
> r <- magick::image_read(as_bm_pixmap(m))
> rt <- bm_extend(r, value = "red", top = 1L)
> print(inherits(rt, "magick-image"))
[1] TRUE

> print(`as_bm_pixmap.magick-image`(rt))
[31m█[39m[31m█[39m
[33m█[39m[33m█[39m
[34m█[39m[34m█[39m

> rr <- bm_extend(r, value = "red", right = 1L)
> print(`as_bm_pixmap.magick-image`(rr))
[33m█[39m[33m█[39m[31m█[39m
[34m█[39m[34m█[39m[31m█[39m

> rb <- bm_extend(r, value = "red", bottom = 1L)
> print(`as_bm_pixmap.magick-image`(rb))
[33m█[39m[33m█[39m
[34m█[39m[34m█[39m
[31m█[39m[31m█[39m

> rl <- bm_extend(r, value = "red", left = 1L)
> print(`as_bm_pixmap.magick-image`(rl))
[31m█[39m[33m█[39m[33m█[39m
[31m█[39m[34m█[39m[34m█[39m

