code: def keywords2marc(self, key, values):
      
      result_695 = self.get('695', [])
      result_084 = self.get('084', [])
      result_6531 = self.get('6531', [])
  
      for value in values:
          schema = value.get('schema')
          source = value.get('source')
          keyword = value.get('value')
  
          if schema == 'PACS' or schema == 'PDG':
              result_084.append({
                  '2': schema,
                  '9': source,
                  'a': keyword,
              })
          elif schema == 'JACOW':
              result_6531.append({
                  '2': 'JACoW',
                  '9': source,
                  'a': keyword,
              })
          elif schema == 'INSPIRE':
              result_695.append({
                  '2': 'INSPIRE',
                  '9': source,
                  'a': keyword,
              })
          elif schema == 'INIS':
              result_695.append({
                  '2': 'INIS',
                  '9': source,
                  'a': keyword,
              })
          elif source != 'magpie':
              result_6531.append({
                  '9': source,
                  'a': keyword,
              })
  
      self['6531'] = result_6531
      self['084'] = result_084
      return result_695
docs: Populate the ``695`` MARC field.
  
      Also populates the ``084`` and ``6531`` MARC fields through side effects.