SWIFT / BIC Code

const re = new RegExp("^[A-Z]{6}[A-Z0-9]{2}(?:[A-Z0-9]{3})?$", "");
const input = "DEUTDEFF";
const match = input.match(re);
console.log(match ? match[0] : null);

import re

pattern = re.compile(r"^[A-Z]{6}[A-Z0-9]{2}(?:[A-Z0-9]{3})?$")
input_text = "DEUTDEFF"
for m in pattern.finditer(input_text):
    print(m.group(0))

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^[A-Z]{6}[A-Z0-9]{2}(?:[A-Z0-9]{3})?$`)
	input := `DEUTDEFF`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}