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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 list_containers(self):
 """ list all available nspawn containers :return: collection of instances of :class:`conu.backend.nspawn.container.NspawnContainer` """

        data = run_cmd(["machinectl", "list", "--no-legend", "--no-pager"],
                       return_output=True)
        output = []
        reg = re.compile(r"\s+")
        for line in data.split("\n"):
            stripped = line.strip()
            if stripped:
                parts = reg.split(stripped)
                name = parts[0]
                output.append(self.ContainerClass(None, None, name=name))
        return output