code: def cache_mem(self):
      return self._cache_mem
  
imports: from urllib.parse import urlparse
  from ...utils import parse_readable_size, calc_size_by_str
  from ..kubernetes.config import ContainerEnvConfig
label_desc: Use image node_id 3 for calling the MarsWorkerSpecConfig obj's underlying member method code with example usage: obj.cache_mem() and returns: self