Go lang conversion from ISO-3166-1 two-letter codes to flag emoji

get-flag.go

// To run this on the Go Playground: https://go.dev/play/p/9na7SU0ExdD

package main

import "fmt"

func main() {
	country := "PT"

	fmt.Printf("%s — Decimal: %d %d Hex: %#[1]x %#x\n", country, rune(country[0]), rune(country[1]))
	fmt.Printf("Difference: %d (hex: %#[1]x)\n", 0x1F1E6-0x0041)
	fmt.Printf("First letter + difference: %d (hex: %#[1]x) Type: %[1]T\n", rune(country[0])+127397)
	fmt.Printf("Second letter + difference: %d (hex: %#[1]x) Type: %[1]T\n", rune(country[1])+127397)
	fmt.Println("Flag: ", getFlag(country))
}

// ISO-3166-1 two-letter country codes to flag emoji.
func getFlag(countryCode string) string {
	// 0x1F1E6 - REGIONAL INDICATOR SYMBOL LETTER A
	// 0x1F1FF - REGIONAL INDICATOR SYMBOL LETTER Z
	// 0x0041 — LATIN CAPITAL LETTER A
	// 0x005A — LATIN CAPITAL LETTER Z

	return string(rune(countryCode[0])+127397) + string(rune(countryCode[1])+127397)
}

Exercise to the reader: check if the two-letter combination is valid (and if there are, indeed, two letters in the string thus passed) and deal with that properly (e.g by displaying a different emoji such as: 🏳️ or 🏴‍☠️ or simply ❌ or 🚫)