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Go lets you do something that feels illegal: shadow `nil`. Yes, `nil` is not a keyword. It is a predeclared identifier, so you can redefine it in a scope, and the compiler will accept it.

After `nil := "a"`, every `nil` in that scope refers to your string variable, not the built-in `nil`. You did not change the language, you just hid the predeclared identifier behind a local name.

So this line: ```go if x == nil ``` is no longer “is x nil?”. It is “is x equal to the string `a`?”. In other words, it becomes: ```go if x == "a" ```

That comparison is false. `x` is a nil interface value, not a string. So the `panic(nil)` never runs, even though it reads like it should. If it did run, it would panic with `"a"`, because `nil` is your string.