text: #!/usr/bin/env python3
  
  # Copyright 2014 Brett Slatkin, Pearson Education Inc.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  # Preamble to mimick book environment
  import logging
  from pprint import pprint
  from sys import stdout as STDOUT
  
  
  # Example 1
  def factorize(number):
      for i in range(1, number + 1):
          if number % i == 0:
              yield i
  
  
  # Example 2
  from time import time
  numbers = [2139079, 1214759, 1516637, 1852285]
  start = time()
  for number in numbers:
      list(factorize(number))
  end = time()
  print('Took %.3f seconds' % (end - start))
  
  
  # Example 3
  from threading import Thread
  
  class FactorizeThread(Thread):
      def __init__(self, number):
          super().__init__()
          self.number = number
  
      def run(self):
          self.factors = list(factorize(self.number))
  
  
  # Example 4
  start = time()
  threads = []
  for number in numbers:
      thread = FactorizeThread(number)
      thread.start()
      threads.append(thread)
  
  
  # Example 5
  for thread in threads:
      thread.join()
  end = time()
  print('Took %.3f seconds' % (end - start))
  
  
  # Example 6
  import select, socket
  
  # Creating the socket is specifically to support Windows. Windows can't do
  # a select call with an empty list.
  def slow_systemcall():
      select.select([socket.socket()], [], [], 0.1)
  
  
  # Example 7
  start = time()
  for _ in range(5):
      slow_systemcall()
  end = time()
  print('Took %.3f seconds' % (end - start))
  
  
  # Example 8
  start = time()
  threads = []
  for _ in range(5):
      thread = Thread(target=slow_systemcall)
      thread.start()
      threads.append(thread)
  
  
  # Example 9
  def compute_helicopter_location(index):
      pass
  
  for i in range(5):
      compute_helicopter_location(i)
  for thread in threads:
      thread.join()
  end = time()
  print('Took %.3f seconds' % (end - start))
  