code: def vizlib_binary_features(span1, span2):
      
      if same_page((span1, span2)):
          yield "SAME_PAGE", DEF_VALUE
  
          if is_horz_aligned((span1, span2)):
              yield "HORZ_ALIGNED", DEF_VALUE
  
          if is_vert_aligned((span1, span2)):
              yield "VERT_ALIGNED", DEF_VALUE
  
          if is_vert_aligned_left((span1, span2)):
              yield "VERT_ALIGNED_LEFT", DEF_VALUE
  
          if is_vert_aligned_right((span1, span2)):
              yield "VERT_ALIGNED_RIGHT", DEF_VALUE
  
          if is_vert_aligned_center((span1, span2)):
              yield "VERT_ALIGNED_CENTER", DEF_VALUE
docs: Visual-related features for a pair of spans