title: send "hi" to all contacts in telegram using telethon
body: <p>I use telethon in python3.7.
  I want to get a list for all me contacts and send &quot;hi&quot; to them.</p>
  <p>code:</p>
  <pre><code>async def main():
  
  try:
      async with TelegramClient('anon', api_id, api_hash) as client:
          result = await client(functions.contacts.GetContactsRequest(
          hash=0
          ))
          await print(result.stringify())
  except Exception as e:
      print(e)
  
  for u in result.users:
      await client.send_message(InputPeerUser(u.id, u.access_hash), &quot;hi&quot;)
  
  with client:
      client.loop.run_until_complete(main())
  </code></pre>
  <p>But I got the error:     raise ConnectionError('Cannot send requests while disconnected')
  ConnectionError: Cannot send requests while disconnected</p>