code: def __init__(self, chain, is_start, is_end, is_representative):
      self.chain = chain
      self.is_start = is_start
      self.is_end = is_end
      self.is_representative = is_representative
  
label_desc: Use image node_id 1 to create a new CorefAttachment object  with example: obj = CorefAttachment(chain, is_start, is_end, is_representative)