code: def canonicalize_clusters(clusters):
      """
      The CONLL 2012 data includes 2 annotatated spans which are identical,
      but have different ids. This checks all clusters for spans which are
      identical, and if it finds any, merges the clusters containing the
      identical spans.
      """
      merged_clusters = []
      for cluster in list(clusters.values()):
          cluster_with_overlapping_mention = None
          for mention in cluster:
              # Look at clusters we have already processed to
              # see if they contain a mention in the current
              # cluster for comparison.
              for cluster2 in merged_clusters:
                  if mention in cluster2:
                      # first cluster in merged clusters
                      # which contains this mention.
                      cluster_with_overlapping_mention = cluster2
                      break
              # Already encountered overlap - no need to keep looking.
              if cluster_with_overlapping_mention is not None:
                  break
          if cluster_with_overlapping_mention is not None:
              # Merge cluster we are currently processing into
              # the cluster in the processed list.
              cluster_with_overlapping_mention.update(cluster)
          else:
              merged_clusters.append(set(cluster))
      return [list(c) for c in merged_clusters]
  
file_path: magnitude/pymagnitude/third_party/allennlp/data/dataset_readers/coreference_resolution/conll.py
imports: from __future__ import absolute_import
  import logging
  import collections
  from allennlp.common.file_utils import cached_path
  from allennlp.data.dataset_readers.dataset_reader import DatasetReader
  from allennlp.data.fields import Field, ListField, TextField, SpanField, MetadataField, SequenceLabelField
  from allennlp.data.instance import Instance
  from allennlp.data.tokenizers import Token
  from allennlp.data.token_indexers import SingleIdTokenIndexer, TokenIndexer
  from allennlp.data.dataset_readers.dataset_utils import Ontonotes, enumerate_spans
label_desc: Use image node_id 1 for calling a global function with example usage: canonicalize_clusters(clusters) and returns: unknown