Show example on how to get all members from a chat

Retrieving-all-chat-members.md

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+In order to get all the members from a mega-group or channel, you need to use [`GetParticipantsRequest`](https://lonamiwebs.github.io/Telethon/methods/channels/get_participants.html). As we can see it needs an [`InputChannel`](https://lonamiwebs.github.io/Telethon/methods/channels/get_participants.html), (passing the mega-group or channel you're going to use will work), and a mandatory [`ChannelParticipantsFilter`](https://lonamiwebs.github.io/Telethon/types/channel_participants_filter.html). The closest thing to "no filter" is to simply use [`ChannelParticipantsSearch`](https://lonamiwebs.github.io/Telethon/constructors/channel_participants_search.html) with an empty `'q'` string.
+
+If we want to get *all* the members, we need to use a moving offset and a fixed limit:
+
+```python
+from telethon.tl.functions.channels import GetParticipantsRequest
+from telethon.tl.types import ChannelParticipantsSearch
+from time import sleep
+
+offset = 0
+limit = 100
+all_participants = []
+
+while True:
+    participants = client(GetParticipantsRequest(
+        channel, ChannelParticipantsSearch(''), offset, limit
+    ))
+    if not participants.users:
+        break
+    all_participants.extend(participants.users)
+    offset += limit
+    sleep(1)
+```
+
+Note that `GetParticipantsRequest` returns [`ChannelParticipants`](https://lonamiwebs.github.io/Telethon/constructors/channels/channel_participants.html), which may have more information you need (like the role of the participants, total count of members, etc.)