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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 free(self, units="MiB"):
 """ Returns the free size in the given units. Default units are MiB. *Args:* """

        self.open()
        size = lvm_pv_get_free(self.handle)
        self.close()
        return size_convert(size, units)