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_08_metaclasses/exercise_01/solution_00.py

@@ -0,0 +1,16 @@
+# Create a metaclass to test if attributes/methods are available.
+
+class ExpectedAttrsMeta(type):
+    _expected_attrs = ['buy', 'sell']
+
+    def __new__(cls, name, bases, attrs):
+        for attr in cls._expected_attrs:
+            if attr not in attrs:
+                raise AttributeError(
+                    f'{attr} attribute is missing from {name} class'
+                )
+        return super().__new__(cls, name, bases, attrs)
+
+
+class Trade(metaclass=ExpectedAttrsMeta):
+    pass