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// Higher-Order Functions & Callback

// ¹. A higher order function takes a function as a parameter.
// ². A callback is a function (() => {...}) that is passed as an argument.

const higherOrderFunction¹= (callback²) => {
   return callback();
}

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	Create	Read	Update
Object.freeze()	❌	✅	❌
Object.seal()	❌	✅	✅

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// keyof
// creates a type based on provided obkect keys
type Lusophone = keyof {Brasil: 🇧🇷, Angola: 🇦🇴, "Cape Verde": 🇨🇻} // Lusophone = "Brasil" | "Angola" | "Cape Verde"

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// Rebuilding Utility Types
// T = Type; K = Keys; U = Union;

// Nullable
type MyNullable<T> = T | null;
type MyNullableTest = MyNullable<🍓>; // MyNullableTest = 🍓 | null

// Non-Nullable (filter != null | undefined)
type MyNonNullable<T> = T extends null | undefined ? never : T;
type MyNonNullableTest = MyNullable<🍊 | 🥝 | null | undefined> // MyNonNullableTest = 🍊 | 🥝

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