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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def update_ssh_config(self, path="~/.ssh/config"):
 """Put the DNS into the ssh config file."""

        # Read the config file #
        import sshconf
        config = sshconf.read_ssh_config(os.path.expanduser(path))
        # In case it doesn't exist #
        if not config.host(self.instance_name): config.add(self.instance_name)
        # Add the new DNS #
        config.set(self.instance_name, Hostname=self.dns)
        # Write result #
        config.write(os.path.expanduser(path))