def METHOD_NAME(connection_string: str) -> bool:
    # determines if given connection string is already among connected or connecting peers
    endpoint_url = connection_string.replace('//', '')
    # ignore peers that we're already trying to connect
    if endpoint_url in self.manager.connections.iter_not_ready_endpoints():
        return True
    # remove peers we already know about
    for peer in known_peers:
        if connection_string in peer.entrypoints:
            return True
    return False