bpo-45498: fix csv dictReader code example

[AkechiShiro]

Fixes an example in the documentation.
Replacing print(row) by print(reader) in DictReader for the csv lib.

https://bugs.python.org/issue45498

[smontanaro]

The current code looks fine to me. Here's a simple session:

>>> import csv
>>> with open('names.csv', newline='') as csvfile:
...     reader = csv.DictReader(csvfile)
...     for row in reader:
...         print(row['first_name'], row['last_name'])
... 
Eric Idle
John Cleese
>>> print(reader)
<csv.DictReader object at 0x7f06c1619dc0>
>>> print(row)
{'first_name': 'John', 'last_name': 'Cleese'}

[AkechiShiro]

Hi @smontanaro, could you explain to me why the row variable is still defined ? It does indeed work, but the row variable should be only defined inside the scope of the for loop no ?

[smontanaro]

The for statement doesn't introduce a new scope. (Nor does the with statement except for the as variable, so reader survives as well.)