code: def _eval(self, threshold: float):
      if self._test_idx is not None:
          triplets = self._triplets[self._test_idx]  # type: ignore
          score = self._score(triplets)
          score = len(score[score >= threshold]) / len(score)  # type: ignore
          return score
      else:
          log("WARNING: train_split must be < 1 for _eval()")
  
imports: import logging
  import numpy
  import pandas
  from typing import Optional, Union, Callable, List, TYPE_CHECKING, Any, Tuple
  from .PlotterBase import Plottable
  from .compute.ComputeMixin import ComputeMixin
label_desc: Use image node_id 12 for calling the HeterographEmbedModuleMixin obj's underlying member method code with example usage: obj._eval(threshold) and returns: score