Errata

>>> name = 'Guido'
>>> n = 37
>>> '%(name) has %(n) messages.' % vars()
'Guido has 37 messages.'
>>>
missing 's' after '%()', the correct pattern should be:
'%(name)s has %(n)s messages.' % vars()

The slice positions are wrongly calculated.

Existing in Book:
record = '....................100 .......513.25 ..........'
cost = int(record[20:32]) * float(record[40:48])
SHARES = slice(20,32)
PRICE = slice(40,48)


Corrected One:
record = '....................100 .......513.25 ..........'
cost = int(record[20:23]) * float(record[31:38])
SHARES = slice(20,23)
PRICE = slice(31,38)

in the book, it shows:

>>> list(compress(addresses, more5))
['5800 E 58TH', '4801 N BROADWAY','1039 W GRANVILLE']

the correct result should be:
>>> list(compress(addresses, more5))
['5800 E 58TH', '1060 W ADDISON', '4801 N BROADWAY']

You should probably put a comma after '2122 N CLARK', because the output is quite confusing as it is now.
If you do, make sure to adjust the following code fragment as well:

>>> list(compress(addresses, more5))
['5800 E 58TH', '4801 N BROADWAY', '1039 W GRANVILLE']

should be:
>>> list(compress(addresses, more5))
['5800 E 58TH', '1060 W ADDISON', '4801 N BROADWAY']

using Python 3.6.5

>>> name = 'Guido'
>>> n = 37
>>> '%(name) has %(n) messages.' % vars()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: unsupported format character 'm' (0x6d) at index 17
>>>

PRINT = r'(P<PRINT>print)'
NAME = r'(P<NAME>[a-zA-Z_][a-zA-Z_0-9]*)'

the pattern is (?P<name>), missing “?”

The paragraph states: "When a value is exactly halfway between two choices, the behavior of round is to round
to the nearest even digit. That is, values such as 1.5 or 2.5 both get rounded to 2.", but round(2.5) evaluates to 3.0 . (Using Python 2.6.9)

The Python documentation for the round() function states: "... if two multiples are equally close, rounding is done away from 0 (so. for example, round(0.5) is 1.0 and round(-0.5) is -1.0)."
(https://docs.python.org/2/library/functions.html#round)

>>>print('This is a test', file= s)
15

Nothing is output under Python 3.8.1

>>>s.write(b'binary data')
>>>

"11" is output

It is true that "itertools.chain()" would not work here, but "itertools.chain.from_iterable()" would do the trick!

Recipe 4.14 - Flattening a nested sequence:
Calling flatten('h', type(None)) will lead to infinite recursion since a string is always iterable, even if only one character.
Hence the generator as written cannot be used to flatten a string.

Chrapter 5, Recipe 5.3. First code example in the discussion section, usage of str.join() method is incorrect.
It is written:
print(','.join('ACME', '50', '91.5'))
A possible solution is to add the strings into a tuple or list:
print(','.join(('ACME', '50', '91.5')))

PRINT = r'(P<PRINT>...
NAME = r'(P<NAME>...

Both are invalid regular expressions - need ? between ( and P

>>>print(','.join('ACME', '50', '91.5'))
Under Python 3.8.1, this results in:
"TypeError: join() takes exactly one argument (3 given)"

needs to be:
print(','.join(('ACME', '50', '91.5')))

Should be
logname = name if name is not None else func.__module__
...
log msg = message if message is not None else func.__name__

In an earlier chapter you discuss how important it is to check for None using, for example, "if x is None" instead of "if not x"

class Person:
def __init__(self, name, age):
self.name = name
self.age = age

should be

class Person:
def __init__(self, name, age):
self._name = name
self._age = age

the underscores for the private class variables went missing (as the @property @name/age.setter use _name and _age).

The method does:

raise NotImplemented('must implement')

But it should instead:

raise NotImplementedError('must implement')

because NotImplemented is not an exception, but a special value used when overloading operators, and NotImplemented is not callable, so the method as implemented actually raises a different exception:

TypeError: 'NotImplementedType' object is not callable

For this to become a proper server and an exact functional equivalent of
the first example, the code in echo_client(q) needs to be wrapped in 'while True:'
Otherwise, the server will only process the first 'nworkers' clients and then just hang there doing nothing, because all the worker threads will have exited by then.