Understanding Server Connections: A List of Established Links

`conns` is a list of connections that have been established by the server. It's a list of tuples, where each tuple contains the connection ID and the address of the client that made the connection.

Here's an example of what `conns` might look like:
```
conns = [
('127.0.0.1', 56789), # connection from 127.0.0.1 on port 56789
('192.168.1.1', 22222), # connection from 192.168.1.1 on port 22222
...
]
```
The `conns` list is used by the server to keep track of the active connections and to handle incoming requests. When a new connection is established, the server adds the connection ID and address of the client to the `conns` list. When a connection is closed, the server removes the corresponding tuple from the `conns` list.