code: def collaborations(self, key, value):
      
      result = []
  
      for g_value in force_list(value.get('g')):
          collaborations = normalize_collaboration(g_value)
          if len(collaborations) == 1:
              result.append({
                  'record': get_record_ref(maybe_int(value.get('0')), 'experiments'),
                  'value': collaborations[0],
              })
          else:
              result.extend({'value': collaboration} for collaboration in collaborations)
  
      return result
docs: Populate the ``collaborations`` key.