anchor.diff:      | 'overlaps'
       | 'parameter'
       | 'per'
  +    | 'point'
       | 'predecessor'
       | 'private'
       | 'properly'
  
positive.code:     | 'or'
      | 'or on'
      | 'per'
      | 'properly'
      | 'return'
      | 'same'
  
negative.code:     | 'overlaps'
      | 'parameter'
      | 'per'
      | 'point'
      | 'predecessor'
      | 'private'
      | 'properly'
  