def to_line(self):
if self.valid:<EOL><INDENT>return "<STR_LIT>".format(<EOL>"<STR_LIT:U+002C>".join(self.hostnames),<EOL>self.key.get_name(),<EOL>self.key.get_base64(),<EOL>)<EOL><DEDENT>return None<EOL>
Returns a string in OpenSSH known_hosts file format, or None if
the object is not in a valid state.  A trailing newline is
included.