Returns the file system type (xfs, ext4) of a given device

def _get_fs(thin_pathname):
        """
        Returns the file system type (xfs, ext4) of a given device
        """
        cmd = ['lsblk', '-o', 'FSTYPE', '-n', thin_pathname]
        fs_return = util.subp(cmd)
        return fs_return.stdout.strip()