docstr: A possibly negative measure of the free cores in millicpu.
  
  See free_cores_mcpu_nonnegative for a more useful property.
docstr_tok: ["A","possibly","negative","measure","of","the","free","cores","in","millicpu",".","See","free_cores_mcpu_nonnegative","for","a","more","useful","property","."]
code: def free_cores_mcpu(self):
      """A possibly negative measure of the free cores in millicpu.
  
      See free_cores_mcpu_nonnegative for a more useful property.
      """
      return self._free_cores_mcpu
  
imports: import base64
  import json
  import logging
  import secrets
  from typing import Dict, Optional
  import aiohttp
  from gear import Database, transaction
  from hailtop import httpx
  from hailtop.humanizex import naturaldelta_msec
  from hailtop.utils import retry_transient_errors, time_msecs, time_msecs_str
  from ..cloud.utils import instance_config_from_config_dict
  from ..globals import INSTANCE_VERSION
  from ..instance_config import InstanceConfig
label_desc: Use image node_id 4 for calling the Instance obj's underlying member method code with example usage: obj.free_cores_mcpu() and returns: self