code: def add_mention(self, mention: MentionData) -> None:
      if mention is not None:
          mention.predicted_coref_chain = self.coref_chain
          self.mentions.append(mention)
          self.cluster_strings.append(mention.tokens_str)
          self.mentions_corefs.add(mention.coref_chain)
  
file_path: nlp-architect/nlp_architect/common/cdc/cluster.py
imports: from typing import List
  from nlp_architect.common.cdc.mention_data import MentionData
label_desc: Use image node_id 3 for calling the Cluster obj's underlying member method code with example usage: obj.add_mention(mention) without return types