code: def abstracts(self, key, value):
      
      result = []
  
      source = force_single_element(value.get('9'))
  
      for a_value in force_list(value.get('a')):
          result.append({
              'source': source,
              'value': a_value,
          })
  
      return result
docs: Populate the ``abstracts`` key.