Függvények típusozása

function add(a: number, b: number): number {
  return a + b
}

function greet(name: string): string {
  return "Hello, " + name
}

function logUser(name: string): void {
  console.log("Felhasználó:", name)
}

const multiply = (a: number, b: number): number => a * b
const greetArrow = (name: string): string => `Hello, ${name}`

function createUser(name: string, age?: number): string {
  if (age !== undefined) return `${name} (${age})`
  return name
}

function createTag(content: string, tag: string = "div"): string {
  return `<${tag}>${content}</${tag}>`
}

function sum(...numbers: number[]): number {
  return numbers.reduce((acc, n) => acc + n, 0)
}

type MathOperation = (a: number, b: number) => number

const addOp: MathOperation = (a, b) => a + b
const subtractOp: MathOperation = (a, b) => a - b

function format(value: string): string
function format(value: number): string
function format(value: string | number): string {
  if (typeof value === "number") return value.toFixed(2)
  return value.trim()
}