rateLimiter.acquire(1); // R1.00, to repay previous

    rateLimiter.setRate(2.0); // update the rate!

    rateLimiter.acquire(1); // R1.00, to repay previous (the previous was under the old rate!)
    rateLimiter.acquire(2); // R0.50, to repay previous (now the rate takes effect)
    rateLimiter.acquire(4); // R1.00, to repay previous
    rateLimiter.acquire(1); // R2.00, to repay previous

    rateLimiter.acquire(1); // R1.00, to repay previous

    rateLimiter.setRate(2.0); // update the rate!

    rateLimiter.acquire(1); // R1.00, to repay previous (the previous was under the old rate!)
    rateLimiter.acquire(2); // R0.50, to repay previous (now the rate takes effect)
    rateLimiter.acquire(4); // R1.00, to repay previous
    rateLimiter.acquire(1); // R2.00, to repay previous