Added example solutions to several chapters. Feel free to create a pull request with your answers. Also for the chapters that have no solutions yet :)

CH_07_generators_and_coroutines/exercise_01/solution_00.py

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+# Create a generator similar to `itertools.islice()` that allows for a 
+# negative step so you can execute `some_list[20:10:-1]`.
+import itertools
+
+
+def islice(iterable, start, stop, step):
+    if step > 0:
+        assert start <= stop, 'start must be less than stop'
+        yield from itertools.islice(iterable, start, stop, step)
+    else:
+        assert start >= stop, 'start must be greater than stop for negative step'
+
+        output = []
+        for i, item in enumerate(iterable):
+            if i >= stop:
+                output.append(item)
+            if i >= start:
+                break
+
+        yield from reversed(output)
+
+
+def main():
+    some_iterable = iter(range(100))
+    print(list(islice(some_iterable, 20, 10, -1)))
+
+    print(list(islice(some_iterable, 10, 20, 1)))
+
+
+if __name__ == '__main__':
+    main()

CH_07_generators_and_coroutines/exercise_02/solution_00.py

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+# Create a class that wraps a generator so it becomes sliceable by using 
+# `itertools.islice()` internally.
+import itertools
+
+
+class SliceableGenerator:
+    def __init__(self, gen):
+        self.gen = gen
+
+    def __getitem__(self, index):
+        return list(itertools.islice(self.gen, index.start, index.stop))
+
+
+def main():
+    generator = SliceableGenerator(itertools.count())
+    print(generator[10:20])
+
+
+if __name__ == '__main__':
+    main()
+

CH_07_generators_and_coroutines/exercise_03/solution_00.py

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+# Write a generator for the Fibonacci numbers.
+
+def fibonacci():
+    a, b = 0, 1
+    while True:
+        yield a
+        a, b = b, a + b
+
+
+def main():
+    fib = fibonacci()
+    for _ in range(10):
+        print(next(fib))
+
+
+if __name__ == '__main__':
+    main()
+

CH_07_generators_and_coroutines/exercise_04/solution_00.py

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+# Write a generator that uses the sieve of Eratosthenes to generate prime 
+# numbers.
+
+import itertools
+
+
+def generate_primes():
+    '''Generate prime numbers using the sieve of Eratosthenes.'''
+    primes = []
+    for i in itertools.count(2):
+        if all(i % prime != 0 for prime in primes):
+            primes.append(i)
+            yield i
+
+
+def main():
+    primes = generate_primes()
+    for _ in range(20):
+        print(next(primes))
+
+
+if __name__ == '__main__':
+    main()