title: Limiting/throttling the rate of HTTP requests in GRequests
body: <p>I'm writing a small script in Python 2.7.3 with <a href="https://github.com/kennethreitz/grequests" rel="noreferrer">GRequests</a> and lxml that will allow me to gather some collectible card prices from various websites and compare them. Problem is one of the websites limits the number of requests and sends back HTTP error 429 if I exceed it.</p>
  
  <p>Is there a way to add throttling the number of requests in GRequestes so that I don't exceed the number of requests per second I specify?
  Also - how can I make GRequestes retry after some time if HTTP 429 occurs?</p>
  
  <p>On a side note - their limit is ridiculously low. Something like 8 requests per 15 seconds. I breached it with my browser on multiple occasions just refreshing the page waiting for price changes.</p>