'ExtraSpecs object holds extra_specs for the instance.'

def __init__(self, cpu_limits=None, hw_version=None, storage_policy=None, cores_per_socket=None, memory_limits=None, disk_io_limits=None, vif_limits=None):

    self.cpu_limits = (cpu_limits or Limits())
    self.memory_limits = (memory_limits or Limits())
    self.disk_io_limits = (disk_io_limits or Limits())
    self.vif_limits = (vif_limits or Limits())
    self.hw_version = hw_version
    self.storage_policy = storage_policy
    self.cores_per_socket = cores_per_socket
