I have a Python script where I fetch messages of a channel using the following code:

entity = InputPeerChannel(int(chat_id), int(chat_hash))

async for message in client.iter_messages(entity, reverse = True, offset_date = offset_date):
#Some stuff to save messages

This works perfectly fine with channels, however I also have groups for which I get the ChannelInvalidError. Which function do I have to use to fetch messages for groups if I have their chat_id and access_hash?