Issue on page /book/pure_python/dictionaries.html

[rameshm76]

Firstly, Amazing work on this book.

The merging of maps need more attention:

Consider d1 with "year" is having a different value than d2

d1 = {"version": "3.11", "language": "Python", "year": 2991}

Then the results vary a bit when duplicate keys exists on both sides.

First one win:
d7 = ChainMap(d1, d2)
d8 = dict(d2, **d1)

Last one win:
d1 |= d2
d3 = d1 | d2
d6 = dict(list(d1.items()) + list(d2.items()))
d1.update(d2.copy())
d5 = {**d1, **d2}

To deliver consistent results:
d7 = ChainMap(d2, d1)
d8 = dict(d1, **d2)

I liked ChainMap as it is clear which one takes precedence