buffers, buffers everywhere...

packages/client/lib/commands/DECRBY.ts

@@ -1,6 +1,11 @@
+import { RedisCommandArgument, RedisCommandArguments } from '.';
+
 export const FIRST_KEY_INDEX = 1;
 
-export function transformArguments(key: string, decrement: number): Array<string> {
+export function transformArguments(
+    key: RedisCommandArgument,
+    decrement: number
+): RedisCommandArguments {
     return ['DECRBY', key, decrement.toString()];
 }