import time

def start():
    return {"_start": time.perf_counter_ns()}

def end(stamp):
    elapsed_ns = time.perf_counter_ns() - stamp["_start"]
    elapsed_ms = elapsed_ns / 1_000_000
    print(f"[ntropy] {elapsed_ms:.2f}ms")
    stamp["_start"] = time.perf_counter_ns()
    return elapsed_ms