correct semaphore usage

utils/helpers.py

@@ -38,16 +38,12 @@ class AsyncCrawler(object):
         docstring
         '''
         urls = set()
-        async with self.semaphore:
         source = await self.get_source(url)
         if source:
             # add the URL we've just crawled
             self.crawled.add(url)
             for new_url in self.find_all_urls(source):
                 urls.add(new_url)
-                # urls_to_crawl = self.find_all_urls(source)
-                # for new_url in urls_to_crawl:
-                #     urls.add(new_url)
 
         return urls
 
@@ -71,6 +67,7 @@ class AsyncCrawler(object):
         Obtains the page's source.
         '''
         print('semaphore held for {0}'.format(url))
+        async with self.semaphore:
             async with self.client_session.get(url, timeout=5) as resp:
                 try:
                     source = await resp.read()