code: def describe_index(self, field_name, collection_name=None):
      # stats = self.get_stats()
      tmp_collection_name = (
          self._collection_name
          if collection_name is None
          else collection_name
      )
      info = self._milvus.describe_index(
          tmp_collection_name, field_name
      )
      logger.info(info)
      index_info = {
          "index_type": "flat",
          "metric_type": None,
          "index_param": None,
      }
      if info:
          index_info = {
              "index_type": info["index_type"],
              "metric_type": info["metric_type"],
              "index_param": info["params"],
          }
          # transfer index type name
          for k, v in INDEX_MAP.items():
              if index_info["index_type"] == v:
                  index_info["index_type"] = k
      return index_info
  
imports: import random
  import logging
  import time
  from multiprocessing import Process
  from pymilvus import Milvus, DataType
  import utils
  import config
  from milvus_benchmark.runners import utils
label_desc: Use image node_id 19 for calling the MilvusClient obj's underlying member method code with example usage: obj.describe_index(field_name, collection_name) and returns: index_info