Add generator test

aufgabe4/why_generators_matter.py

+#!/usr/bin/env python3
+
+from memory_profiler import profile
+from memory_profiler import memory_usage
+
+print('Memory usage before : {}MB'.format(memory_usage()))
+
+def gen(n):
+    for i in range(n):
+        obj = {'id': i}
+        yield obj
+
+
+def it(n):
+    l = list()
+    for i in range(n):
+        l.append({'id': 1})
+
+    return l
+
+a = gen(1000000)
+
+print('Memory usage after : {}MB'.format(memory_usage()))