<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def register(self, correlation_id, key, connection):
 """ Registers connection parameters into the discovery service. :param correlation_id: (optional) transaction id to trace execution through call chain. :param key: a key to uniquely identify the connection parameters. :param connection: a connection to be registered. """

        item = DiscoveryItem()
        item.key = key
        item.connection = connection
        self._items.append(item)