new challenge: empty-tuple (intermediate) (#94)

Author: F-park

challenges/intermediate-empty-tuple/hints.md

@@ -0,0 +1 @@
+Check out [annotating-tuples](https://docs.python.org/zh-cn/3/library/typing.html#annotating-tuples)

challenges/intermediate-empty-tuple/question.py

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+"""
+TODO:
+
+foo should accept a empty tuple argument.
+"""
+
+
+def foo(x):
+    pass
+
+
+## End of your code ##
+foo(())
+foo((1))  # expect-type-error

challenges/intermediate-empty-tuple/solution.py

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+"""
+TODO:
+
+foo should accept a empty tuple argument.
+"""
+
+
+def foo(x: tuple[()]):
+    pass
+
+
+## End of your code ##
+foo(())
+foo((1))  # expect-type-error