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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 get_cpu_props(cls, family, arch='x86'):
 """ Get CPU info XML Args: family(str):
 CPU family arch(str):
 CPU arch Returns: lxml.etree.Element: CPU xml Raises: :exc:`~LagoException`: If no such CPU family exists """


        cpus = cls.get_cpus_by_arch(arch)
        try:
            return cpus.xpath('model[@name="{0}"]'.format(family))[0]
        except IndexError:
            raise LagoException('No such CPU family: {0}'.format(family))