def RecreateInstanceDisks(r, instance, disks=None, nodes=None):
    """Recreate an instance's disks.

    @type instance: string
    @param instance: Instance name
    @type disks: list of int
    @param disks: List of disk indexes
    @type nodes: list of string
    @param nodes: New instance nodes, if relocation is desired
    @rtype: string
    @return: job id
    """
    body = {}
    if disks is not None:
        body['disks'] = disks
    if nodes is not None:
        body['nodes'] = nodes
    return r.request('post', '/2/instances/%s/recreate-disks' % instance,
        content=body)
