anchor.diff:  >>> conn.commit()
   >>> conn.notifications[0][1]
   'aliens_landed'
  -
  -----
  -
  -
  -=== Parameters Are For Data Not Identifiers
  -
  -In PostgreSQL parameters can only be used for
  -https://www.postgresql.org/docs/current/xfunc-sql.html#XFUNC-SQL-FUNCTION-ARGUMENTS[data values, not identifiers]. Sometimes this might not work as expected,
  -for example the following fails:
  -
  -[source,python]
  -----
  ->>> cursor.execute("SELECT 'silo 1' limit %s", ('ALL',))
  -Traceback (most recent call last):
  -pg8000.core.ProgrammingError: ...
  ->>> conn.rollback()
  -
  -----
  -
  -Instead the https://www.postgresql.org/docs/current/sql-select.html[docs say]
  -that you can send `null` as an alternative to `ALL`, which does work:
  -
  -[source,python]
  -----
  ->>> cur = conn.cursor()
  ->>> cur.execute("SELECT 'silo 1' limit %s", (None,))
  -<pg8000.core.Cursor object at ...>
  ->>> cur.fetchone()
  -['silo 1']
   
   ----
   
  
positive.code: (['silo 1'],)
  
  ----
  
  
  === COPY from and to a file
  
negative.code: ----
  
  
  === LIMIT ALL
  
  You might think that the following would work, but in fact it fails:
  
  [source,python]
  ----
  