'Describe an instance\'s RAID arrays.
You must specify at least one of the parameters.
**Required Permissions**: To use this action, an IAM user must
have a Show, Deploy, or Manage permissions level for the
stack, or an attached policy that explicitly grants
permissions. For more information on user permissions, see
`Managing User Permissions`_.
:type instance_id: string
:param instance_id: The instance ID. If you use this parameter,
`DescribeRaidArrays` returns descriptions of the RAID arrays
associated with the specified instance.
:type stack_id: string
:param stack_id: The stack ID.
:type raid_array_ids: list
:param raid_array_ids: An array of RAID array IDs. If you use this
parameter, `DescribeRaidArrays` returns descriptions of the
specified arrays. Otherwise, it returns a description of every
array.'

def describe_raid_arrays(self, instance_id=None, stack_id=None, raid_array_ids=None):

    params = {}
    if (instance_id is not None):
        params['InstanceId'] = instance_id
    if (stack_id is not None):
        params['StackId'] = stack_id
    if (raid_array_ids is not None):
        params['RaidArrayIds'] = raid_array_ids
    return self.make_request(action='DescribeRaidArrays', body=json.dumps(params))
