Add logging module (denoland/deno_std#33)

Original: 25b88bcf8c

logging/handler.ts

@@ -0,0 +1,18 @@
+import { getLevelByName } from "./levels";
+
+export class BaseHandler {
+  level: number;
+  levelName: string;
+
+  constructor(levelName) {
+    this.level = getLevelByName(levelName);
+    this.levelName = levelName;
+  }
+
+  handle(level, ...args) {
+    if (this.level > level) return;
+    return this._log(level, ...args);
+  }
+
+  _log(level, ...args) {}
+}