old_contents: def sum_even_fibonacci_numbers_1():
      f1, f2, s, = 0, 1, 0,
      while f2 < 4000000:
          f2, f1 = f1, f1 + f2
          if f2 % 2 == 0:
              s += f2
      return s
  def sum_even_fibonacci_numbers_2():
      s, a, b = 0, 1, 1
      c = a + b
      while c < 4000000:
          s += c
          a = b + c
          b = a + c
          c = a + b
      return s
  
new_contents: from timeit import timeit
  def sum_even_fibonacci_numbers_1():
      f1, f2, s, = 0, 1, 0,
      while f2 < 4000000:
          f2, f1 = f1, f1 + f2
          if f2 % 2 == 0:
              s += f2
      return s
  def sum_even_fibonacci_numbers_2():
      s, a, b = 0, 1, 1
      c = a + b
      while c < 4000000:
          s += c
          a = b + c
          b = a + c
          c = a + b
      return s
  print "sum_even_fibonacci_numbers_1: {0}".format(timeit("sum_even_fibonacci_numbers_1()", "from __main__ import sum_even_fibonacci_numbers_1;"))
  print "sum_even_fibonacci_numbers_2: {0}".format(timeit("sum_even_fibonacci_numbers_2()", "from __main__ import sum_even_fibonacci_numbers_2;"))
  
subject: Add timeit to measure each python implementation of problem 2