feat: add some utilities

src/program/Clear.ts

@@ -0,0 +1,10 @@
+import type { SimpleStream } from '../utils/SimpleStream'
+import { Program } from './Program'
+
+export class Clear extends Program {
+    async Exec(_: SimpleStream<string>, stdout: SimpleStream<string>, __: string[]): Promise<number> {
+        stdout.emit('\f')
+
+        return 0
+    }
+}