anchor.diff:  :link:https://docs.python.org/3.9/whatsnew/3.9.html
   
   === Dictionary merge and update `a|b` or `a|=b`
  +
  +```python
  +>>> x = {"key1": "value1 from x", "key2": "value2 from x"}
  +>>> y = {"key2": "value2 from y", "key3": "value3 from y"}
  +>>> x | y
  +{'key1': 'value1 from x', 'key2': 'value2 from y', 'key3': 'value3 from y'}
  +>>> y | x
  +{'key2': 'value2 from x', 'key3': 'value3 from y', 'key1': 'value1 from x'}
  +```
  +
   === Type hinting generics in standard collections: `list[str]`, `dict[str, int]` 
   
   == 3.8 
  
positive.code: :link:https://docs.python.org/3.8/whatsnew/3.8.html 
  
  === Assignment expression aka walrus operator `:=`
  ```
  # re search
  discount = 0.0
  if (mo := re.search(r'(\d+)% discount', advertisement)):
  
negative.code: 
  
  === Context manager with paranthesis
  ```python
  with (
      CtxManager1() as example1,
      CtxManager2() as example2,
  