anchor.diff:  
    serial_number  | productivity | fairian_name 
   ----------------+--------------+--------------
  - 356a192b7913b0 |     0.004341 | alice
  - 77de68daecd823 |              | 
  + 356a192b7913b0 |     0.002896 | alice
  + 77de68daecd823 |            0 | 
   (2 rows)
   --------------------------------------------
   
  
positive.code: ------------+------------+------+---------------+-------+--------------+----------------+------
   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 |    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 |     9 | bob          | 77de68daecd823 |  0.9
   farmer     |         29 |   10 |             0 |     8 | bob          | 77de68daecd823 |  0.8
   farmer     |         29 |   10 |             0 |     7 | bob          | 77de68daecd823 |  0.7
  
negative.code:     21 | alice        | bond    |  1000 |        | Issued bond 902ba3cda18838
      22 | david        | work    |    45 |        | Ratified contract fe5dbbcea5ce7e
      22 | alice        | work    |       |     45 | Ratified contract fe5dbbcea5ce7e
      23 | alice        | bond    |       |    955 | Redeemed bond 902ba3cda18838
  (4 rows)
  --------------------------------------------
  
  This new labor contract between her and David issued at click 
  22 appears in the work view:
  
  --------------------------------------------
  fairwinds=> select contract_number, issue_date, term, customer, 
  