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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 guest_create_disks(self, userid, disk_list):
 """Add disks to an existing guest vm. :param userid: (str) the userid of the vm to be created :param disk_list: (list) a list of disks info for the guest. It has one dictionary that contain some of the below keys for each disk, the root disk should be the first element in the list, the format is: {'size': str, 'format': str, 'is_boot_disk': bool, 'disk_pool': str} In which, 'size': case insensitive, the unit can be in Megabytes (M), Gigabytes (G), or number of cylinders/blocks, eg 512M, 1g or just 2000. 'format': optional, can be ext2, ext3, ext4, xfs, if not specified, the disk will not be formatted. 'is_boot_disk': For root disk, this key must be set to indicate the image that will be deployed on this disk. 'disk_pool': optional, if not specified, the disk will be created by using the value from configure file,the format is ECKD:eckdpoolname or FBA:fbapoolname. For example: [{'size': '1g', 'is_boot_disk': True, 'disk_pool': 'ECKD:eckdpool1'}, {'size': '200000', 'disk_pool': 'FBA:fbapool1', 'format': 'ext3'}] In this case it will create one disk 0100(in case the vdev for root disk is 0100) with size 1g from ECKD disk pool eckdpool1 for guest , then set IPL 0100 in guest's user directory, and it will create 0101 with 200000 blocks from FBA disk pool fbapool1, and formated with ext3. """

        if disk_list == [] or disk_list is None:
            # nothing to do
            LOG.debug("No disk specified when calling guest_create_disks, "
                      "nothing happened")
            return

        action = "create disks '%s' for guest '%s'" % (str(disk_list), userid)
        with zvmutils.log_and_reraise_sdkbase_error(action):
            return self._vmops.create_disks(userid, disk_list)