<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 async def scp_to(self, source, destination, user='ubuntu', proxy=False, scp_opts=''):
 """Transfer files to this machine. :param str source: Local path of file(s) to transfer :param str destination: Remote destination of transferred files :param str user: Remote username :param bool proxy: Proxy through the Juju API server :param scp_opts: Additional options to the `scp` command :type scp_opts: str or list """

        if proxy:
            raise NotImplementedError('proxy option is not implemented')

        address = self.dns_name
        destination = '%s@%s:%s' % (user, address, destination)
        await self._scp(source, destination, scp_opts)