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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 _load_ssh_file(self, path):
 """ Attempt to open and parse an SSH config file at ``path``. Does nothing if ``path`` is not a path to a valid file. :returns: ``None``. """

        if os.path.isfile(path):
            old_rules = len(self.base_ssh_config._config)
            with open(path) as fd:
                self.base_ssh_config.parse(fd)
            new_rules = len(self.base_ssh_config._config)
            msg = "Loaded {} new ssh_config rules from {!r}"
            debug(msg.format(new_rules - old_rules, path))
        else:
            debug("File not found, skipping")