Created Joining a public channel (markdown)

Joining-a-public-channel.md

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+Once you have the [entity](Retrieving-an-entity) of the channel you want to join to, you can make use of the [`JoinChannelRequest`](https://lonamiwebs.github.io/Telethon/methods/channels/join_channel.html) to join such channel:
+
+```python
+from telethon.tl.functions.channels import JoinChannelRequest
+from telethon.helpers import get_input_peer
+
+input_channel = get_input_peer(channel)
+client.invoke(JoinChannelRequest(input_channel))
+
+# In the same way, you can also leave such channel
+from telethon.tl.functions.channels import LeaveChannelRequest
+client.invoke(LeaveChannelRequest(input_channel))
+```
+
+For more on channels, check the [`channels` namespace](https://lonamiwebs.github.io/Telethon/methods/channels/index.html).