code: def calculate_metric(self):
      self.all_preds = (
          self.all_pred_answers,
          self.all_pred_starts,
          self.all_pred_ends,
      )
      self.all_targets = (
          self.all_target_answers,
          self.all_target_starts,
          self.all_target_ends,
      )
  
      (
          exact_matches,
          f1_scores_sum,
      ) = self._compute_exact_matches_and_f1_scores_sum(
          self.all_pred_answers,
          self.all_target_answers,
      )
      count = len(self.all_pred_answers)
      metrics = SquadMetrics(
          exact_matches=100.0 * exact_matches / count,
          f1_score=100.0 * f1_scores_sum / count,
          num_examples=count,
          classification_metrics=None,
      )
      return metrics
  
imports: import re
  import string
  from typing import Dict, List, Set, Tuple, Union
  import numpy
  from pytext.common.constants import Stage
  from pytext.metric_reporters.channel import Channel, ConsoleChannel, FileChannel
  from pytext.metric_reporters.metric_reporter import MetricReporter
  from pytext.metrics.squad_metrics import SquadMetrics
  from pytext.utils.data import merge_token_labels_to_slot, parse_slot_string, Slot
  from scipy.optimize import linear_sum_assignment
label_desc: Use image node_id 9 for calling the MultiSpanQAMetricReporter obj's underlying member method code with example usage: obj.calculate_metric() and returns: metrics