code: def num_entities(self):
      self.flush()
      return self.partition.num_entities if self.partition else None
  
imports: import sys
  from numpy import NaN
  from pymilvus import Partition
  from check.func_check import ResponseChecker
  from utils.api_request import api_request
  from common.common_func import param_info
label_desc: Use image node_id 5 for calling the ApiPartitionWrapper obj's underlying member method code with example usage: obj.num_entities() and returns: unknown