anchor.diff:  ------------+------------+------+---------------+-------+--------------+----------------+------
    farmer     |         29 |   10 |             0 |    25 | bob          | 77de68daecd823 |  2.5
    farmer     |         29 |   10 |             0 |    22 | bob          | 77de68daecd823 |  2.2
  - farmer     |         29 |   10 |             0 |    20 | bob          | 77de68daecd823 |    2
  + farmer     |         29 |   10 |             0 |    20 | bob          | 77de68daecd823 |  2.0
    farmer     |         29 |   10 |             0 |    18 | bob          | 77de68daecd823 |  1.8
    farmer     |         29 |   10 |             0 |    16 | bob          | 77de68daecd823 |  1.6
    farmer     |         29 |   10 |             0 |    15 | bob          | 77de68daecd823 |  1.5
    farmer     |         29 |   10 |             0 |    14 | bob          | 77de68daecd823 |  1.4
    farmer     |         29 |   10 |             0 |    13 | bob          | 77de68daecd823 |  1.3
    farmer     |         29 |   10 |             0 |    12 | bob          | 77de68daecd823 |  1.2
  - farmer     |         29 |   10 |             0 |    10 | bob          | 77de68daecd823 |    1
  + farmer     |         29 |   10 |             0 |    10 | bob          | 77de68daecd823 |  1.0
    farmer     |         29 |   10 |             0 |     9 | bob          | 77de68daecd823 |  0.9
    farmer     |         29 |   10 |             0 |     8 | bob          | 77de68daecd823 |  0.8
    farmer     |         29 |   10 |             0 |     7 | bob          | 77de68daecd823 |  0.7
  
positive.code: 
   serial_number  | productivity | fairian_name 
  ----------------+--------------+--------------
   356a192b7913b0 |     0.004341 | alice
   77de68daecd823 |              | 
  (2 rows)
  --------------------------------------------
  
  
negative.code:  7719a1c782a1ba  |         25 |   10 | bob      | vincent  | 77de68daecd823 | farmer
   22d200f8670dbd  |         25 |   10 | bob      | wendy    | 77de68daecd823 | farmer
   632667547e7cd3  |         25 |   10 | bob      | xavier   | 77de68daecd823 | farmer
  (21 rows)
  --------------------------------------------
  
  
  