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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_image_size(self, image_path):
 """Return disk size in bytes"""

        command = 'du -b %s' % image_path
        (rc, output) = zvmutils.execute(command)
        if rc:
            msg = ("Error happened when executing command du -b with"
                   "reason: %s" % output)
            LOG.error(msg)
            raise exception.SDKImageOperationError(rs=8)
        size = output.split()[0]
        return size