Challenge 2: Type Patterns Over an object — Possible Solution
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Program.cs:

static string Describe(object obj) => obj switch
{
    int n => $"an int with value {n}",
    string s => $"a string of length {s.Length}",
    null => "a null reference",
    _ => "something else entirely"
};

Console.WriteLine(Describe(42));
Console.WriteLine(Describe("hello"));
Console.WriteLine(Describe(null));
Console.WriteLine(Describe(3.14));

Output:

    an int with value 42
    a string of length 5
    a null reference
    something else entirely

Explanation:
Each case is a type pattern -- `int n` matches only if obj is
genuinely an int, binding it directly to n with no separate cast, the
same style java1-3's own instanceof pattern matching introduced but
built directly into switch here. The dedicated `null` pattern matches
specifically when obj is null, distinct from any type pattern. The
discard `_` catches every value none of the earlier patterns matched
-- here, a double.

WHY THIS WORKS AS AN ANSWER
------------------------------
This uses the chapter's own type-pattern, null-pattern, and discard-
pattern syntax together in one switch expression, covering four
distinct cases (int, string, null, and an unmatched type) to
demonstrate each pattern kind actually firing correctly.