Используя идентичный код, почему MVS 2019 компилирует этот код, но компилятор Codewars имеет некоторые ошибки?

Задание от codewars:

Write an algorithm that will identify valid IPv4 addresses in dot-decimal format. IPs should be considered valid if they consist of four octets, with values between 0 and 255, inclusive.

Input to the function is guaranteed to be a single string.

Examples Valid inputs:

1.2.3.4 123.45.67.89

Invalid inputs:

1.2.3 1.2.3.4.5 123.456.78.90 123.045.067.089 Note that leading zeros (e.g. 01.02.03.04) are considered invalid.

Мое решение:

class Kata
{
    public static bool is_valid_IP(string ipAddres)
    {
        int ipnumber = 0;

        bool numberChecker(List<char> number)
        {
            string checkNum = null;
            foreach (char symb in number)
            {
                checkNum += symb.ToString();
            }
            try
            {
                byte result = Convert.ToByte(checkNum);
                if (result.ToString() == (checkNum).ToString())
                {
                    ipnumber++;
                    return true;
                }
                else
                    return false;
            }
            catch
            {
                return false;
            }
        }
        bool getOut = false;
        ipAddres = ipAddres + '.';
        char[] ipArray = ipAddres.ToCharArray();
        List<char> check = new List<char>();
        foreach (char symbol in ipArray)
        {
            if (check.Contains('.'))
                break;
            if (symbol == '.')
            {
                getOut = numberChecker(check);
                check.Clear();
            }
            else
                check.Add(symbol);
        }
        if (getOut == true && ipnumber == 4)
        {
            return true;
        }
        else
            return false;
    }
}

code.cs(9,31): error CS1525: Unexpected symbol `(', expecting `,', `;', or `='
code.cs(38,22): error CS1519: Unexpected symbol `=' in class, struct, or interface member declaration
code.cs(38,33): error CS1519: Unexpected symbol `+' in class, struct, or interface member declaration
code.cs(43,19): error CS1519: Unexpected symbol `foreach' in class, struct, or interface member declaration
code.cs(43,35): error CS1519: Unexpected symbol `in' in class, struct, or interface member declaration
code.cs(43,44): error CS1519: Unexpected symbol `)' in class, struct, or interface member declaration
code.cs(44,13): error CS9010: Primary constructor body is not allowed
code.cs(58,14): error CS1519: Unexpected symbol `if' in class, struct, or interface member declaration
code.cs(58,25): error CS1519: Unexpected symbol `==' in class, struct, or interface member declaration
code.cs(58,45): error CS1519: Unexpected symbol `==' in class, struct, or interface member declaration
code.cs(59,13): error CS9010: Primary constructor body is not allowed
code.cs(59,13): error CS8041: Primary constructor already has a body
code.cs(62,16): error CS1519: Unexpected symbol `else' in class, struct, or interface member declaration
code.cs(68,0): error CS1525: Unexpected symbol `}'

🤔 А знаете ли вы, что...
C# позволяет создавать собственные библиотеки классов и использовать их в других проектах.