public static string Digits(this System.Random random, int count)
{
var chars = Enumerable.Range(0, count)
.Select(_ => random.Digit())
.ToArray();
return(new string(chars));
}
public static string PostCode(this System.Random random) =>
$"{new string(random.Chars(2))}{random.Digits(2)} {random.Digit()}{new string(random.Chars(2))}"
.ToUpperInvariant();