Notes on the textbook, Downey, Python for Software Design (printed),
also Think Python (online).

I like the book very much but there are a few examples where a
different style is usually considered better, or where additional
explanation would be helpful.

Exercise 3.5

Downey's solution at thinkpython.com/code/grid.py does not use loops
because he has not yet introduced them in the book.  A more typical
solution would use a 'for' loop, which is shorter, and easier to
generalize to different sized grids.


Section 10.3

 for i in range(len(numbers)):
     numbers[i] = numbers[i] * 2

It is usually better style to use enumerate to get the index number:

 for i, n in enumerate(numbers):
     numbers[i] = n * 2  # here n == numbers[i]


Section 14.5

  try 
    fin = ...
    ...
  except:
    ...

It is usually better style to make the expected exception
explicit, to avoid masking unexpected exceptions:

  try
    fin = ...
    ...
  except IOError:
    ...