Added ago timers

packages/common/src/helpers.ts

@@ -1,10 +1,10 @@
-import { Milliseconds } from './types';
+import { Milliseconds, Timestamp } from './types';
 
 /**
  * PhantomData akin to Rust, because sometimes you need to be smarter than
  * the compiler.
  */
-export abstract class PhantomData<P> { private __PHANTOM__: P }
+export abstract class PhantomData<P> { public __PHANTOM__: P }
 
 /**
  * Opaque type, similar to `opaque type` in Flow, or new types in Rust/C.
@@ -31,3 +31,5 @@ export function sleep(time: Milliseconds): Promise<void> {
         setTimeout(() => resolve(), time);
     });
 }
+
+export const timestamp = Date.now as () => Timestamp;