using System;

using System.Text;

using System.Collections.Generic;

public static class Program

{

    public static void Main()

    {

        Console.WriteLine(StringComparison.CurrentCultureIgnoreCase.To_snake_case());

    }

    public static string To_snake_case<T>(this T value) where T : Enum

    {

        return SnakeCaseHelper<T>.Values.TryGetValue(value, out var name) ? name : null;

    }

​

    private static class SnakeCaseHelper<T> where T : Enum

    {

        public static Dictionary<T, string> Values = new();

​

        static SnakeCaseHelper()

        {

            var names = Enum.GetNames(typeof(T));

            var values = (T[])Enum.GetValues(typeof(T));

            for (var i = 0; i < values.Length; i++)

                Values[values[i]] = GetSnakeCase(names[1]);

        }

​

        static string GetSnakeCase(string text)

        {

            if(text.Length < 2)

                return text;

​

            var sb = new StringBuilder();

            sb.Append(char.ToLowerInvariant(text[0]));

            for(int i = 1; i < text.Length; ++i)

            {

                char c = text[i];

                if(char.IsUpper(c))

                {

                    sb.Append('_');

                    sb.Append(char.ToLowerInvariant(c));

                }

                else

                {

                    sb.Append(c);

                }

            }

            return sb.ToString();

        }

    }

}