public static Dictionary<char, char> NumberToLetterMap { get; } = new Dictionary<char, char>() { { '1', 'i' }, { '3', 'e' }, { '4', 'a' }, { '5', 's' }, { '7', 't' }, { '8', 'b' }, { '0', 'o' } };
public static Dictionary<char, char> LetterToNumberMap { get; } = new Dictionary<char, char>() { { 'i', '1' }, { 'e', '3' }, { 'a', '4' }, { 's', '5' }, { 't', '7' }, { 'b', '8' }, { 'o', '0' } };
private static char NumberToLetter(char c) => NumberToLetterMap.ContainsKey(c) ? NumberToLetterMap[c] : (char)0x00;