code: def add_default_envs(self):
      if self._cpu:
          self.add_env("MARS_CPU_TOTAL", str(self._cpu))
  
      if self._memory:
          self.add_env("MARS_MEMORY_TOTAL", str(int(self._memory)))
  
      if self._modules:
          self.add_env("MARS_LOAD_MODULES", ",".join(self._modules))
  
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 MarsReplicaSpecConfig obj's underlying member method code with example usage: obj.add_default_envs() without return types