Scratch arena, in-place temporary gebs_fmt() macro

example/arena.c

@@ -0,0 +1,26 @@
+#define GEBS_IMPLEMENTATION
+#include "../gebs.h"
+
+typedef struct {
+    int *items;
+    size_t count, capacity;
+} Ints;
+
+int main(void)
+{
+    Gebs_Arena *arena = gebs_arena_make(1024);
+    defer { gebs_arena_destroy(arena); }
+
+    Ints ints = {0};
+    defer { gebs_list_free_alloc(arena, &ints); }
+    for (size_t i = 0; i < 1000; i++) {
+        gebs_list_append_alloc(arena, &ints, i);
+    }
+    for (size_t i = 0; i < ints.count; i++) {
+        printf("%zu\n", i);
+    }
+
+    printf("%s\n", gebs_fmt("Hello formatting %d", 124));
+
+    return 0;
+}