removeSocket method
Removes a socket from the multiplexer's management.
Implementation
void removeSocket(ConnectionId localCid) {
final socket = socketsByCid.remove(localCid);
if (socket != null) {
final peerKey = '${socket.remoteAddress.address}:${socket.remotePort}';
// The address may have other connections; only forget it for this one.
if (identical(socketsByPeer[peerKey], socket)) socketsByPeer.remove(peerKey);
}
}