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Exercises/soln7_1.md

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+# Exercise 7.1 - Solution
+
+```python
+# validate.py
+...
+
+from inspect import signature
+
+def validated(func):
+    sig = signature(func)
+
+    # Gather the function annotations
+    annotations = dict(func.__annotations__)
+
+    # Get the return annotation (if any)
+    retcheck = annotations.pop('return', None)
+
+    def wrapper(*args, **kwargs):
+        bound = sig.bind(*args, **kwargs)
+        errors = []
+
+        # Enforce argument checks
+        for name, validator in annotations.items():
+            try:
+                validator.check(bound.arguments[name])
+            except Exception as e:
+                errors.append(f'    {name}: {e}')
+
+        if errors:
+            raise TypeError('Bad Arguments\n' + '\n'.join(errors))
+
+        result = func(*args, **kwargs)
+
+        # Enforce return check (if any)
+        if retcheck:
+            try:
+                retcheck.check(result)
+            except Exception as e:
+                raise TypeError(f'Bad return: {e}') from None
+        return result
+
+    return wrapper
+```
+
+
+
+[Back](ex7_1.md)