update from Atlas

futures/countries/flags.py

@@ -0,0 +1,62 @@
+"""Download flags of top 20 countries by population
+
+Sequential version
+
+Sample run::
+
+    $ python3 flags.py
+    BD retrieved.
+    BR retrieved.
+    CD retrieved.
+    ...
+    TR retrieved.
+    US retrieved.
+    VN retrieved.
+    20 flags downloaded in 10.16s
+
+"""
+
+import os
+import time
+
+import requests
+
+POP20_CC = ('CN IN US ID BR PK NG BD RU JP '
+            'MX PH VN ET EG DE IR TR CD FR').split()
+
+BASE_URL = 'http://python.pro.br/fluent/data/flags'
+
+DEST_DIR = 'downloads/'
+
+
+def save_flag(img, filename):
+    path = os.path.join(DEST_DIR, filename)
+    with open(path, 'wb') as fp:
+        fp.write(img)
+
+
+def get_flag(cc):
+    url = '{}/{cc}/{cc}.gif'.format(BASE_URL, cc=cc.lower())
+    res = requests.get(url)
+    return res.content
+
+
+def download_many(cc_list):
+    for cc in sorted(cc_list):
+        image = get_flag(cc)
+        print('{} retrieved.'.format(cc))
+        save_flag(image, cc.lower() + '.gif')
+
+    return len(cc_list)
+
+
+def main(download_many):
+    t0 = time.time()
+    count = download_many(POP20_CC)
+    elapsed = time.time() - t0
+    msg = '{} flags downloaded in {:.2f}s'
+    print(msg.format(count, elapsed))
+
+
+if __name__ == '__main__':
+    main(download_many)