class_docstr: Mock metric class to be used in case of prometheus_client import error.
class_docstr_tok: ["Mock","metric","class","to","be","used","in","case","of","prometheus_client","import","error","."]
code: def inc(self, *args, **kwargs):
      pass
  
imports: from typing import Optional
  from ray.dashboard.consts import COMPONENT_METRICS_TAG_KEYS
label_desc: Use image node_id 3 for calling the NullMetric obj's underlying member method code with example usage: obj.inc() without return types