53 static bool is_black(struct rbnode *n)  in is_black()  function
165 		      is_black(get_child(node, 0U)));  in fix_extra_red()
167 		      is_black(get_child(node, 1U)));  in fix_extra_red()
169 		if (is_black(parent)) {  in fix_extra_red()
256 	CHECK(is_black(tree->root));  in rb_insert()
281 		CHECK(is_black(n));  in fix_missing_black()
288 		if (!is_black(sib)) {  in fix_missing_black()
307 		if (((c0 == NULL) || is_black(c0)) && ((c1 == NULL) ||  in fix_missing_black()
308 					is_black(c1))) {  in fix_missing_black()
314 			if (is_black(parent)) {  in fix_missing_black()
481 		if (is_black(node)) {  in rb_remove()
493 		__ASSERT(is_black(node) || is_black(child), "both nodes red?!");  in rb_remove()
521 	return is_black(node);  in z_rb_is_black()