C# Function That Mimics SQL IN-operator

A good question was asked on stackoverflow, and an even better answer received.

How can we rewrite the condition

if (a == x || a == y || a == z)

to make it more readable?

The answer is

public static bool IsIn<T>(this T obj, params T[] collection) {
   return collection.Contains(obj);
}

if (a.IsIn(x, y, z))

PS. Sorry for such a long period with no posting. You know, summer, Sun, beach, sea, +30 and vacation.