add example

docs/index.rst

@@ -31,6 +31,56 @@ Google:
   es  = events(<Google Calendar URL>)
 
 
+Example
+=======
+
+see main.py
+
+.. code:: python
+
+   from icalevents.icalevents import events_async, latest_events, all_done
+   from time import sleep
+
+   if __name__ == '__main__':
+      keys = []
+
+      with open('calendars.txt', mode='r', encoding='utf-8') as f:
+         counter = 1
+
+         while True:
+               line = f.readline()
+               if not line:
+                  break
+
+               name, url = line.split(maxsplit=1)
+               name = name.strip()
+               url = url.strip()
+
+               fix_apple = False
+               if name == 'icloud':
+                  fix_apple = True
+
+               key = "req_%d" % counter
+               counter += 1
+               keys.append(key)
+               events_async(key, url, fix_apple=fix_apple)
+
+      while keys:
+         print("%d request running." % len(keys))
+
+         for k in keys[:]:
+               if all_done(k):
+                  print("Request %s finished." % k)
+                  keys.remove(k)
+
+                  es = latest_events(k)
+
+                  for e in es:
+                     print(e)
+
+         sleep(2)
+
+
 API
 ===