namespace System
{
    // NEW type
    [Flags]
    public enum HexFormattingOptions
    {
        None = 0,
        InsertLineBreaks = 1,
        Lowercase = 2
    }

    // NEW methods on EXISTING type
    public static class Convert
    {
        // Decode from chars
        public static byte[] FromHexCharArray(char[] inArray, int offset, int length) => throw null;
        public static bool TryFromHexChars(ReadOnlySpan<char> chars, Span<byte> bytes, out int bytesWritten) => throw null;

        // Decode from strings
        public static byte[] FromHexString(string s) => throw null;
        public static byte[] FromHexString(ReadOnlySpan<char> chars) => throw null;
        public static bool TryFromHexString(string s, Span<byte> bytes, out int bytesWritten) => throw null;

        // Encode to chars
        public static int ToHexCharArray(byte[] inArray, int offsetIn, int length, char[] outArray, int offsetOut, HexFormattingOptions options = default) => throw null;
        public static bool TryToHexChars(ReadOnlySpan<byte> bytes, Span<char> chars, out int charsWritten, HexFormattingOptions options = default) => throw null;

        // Encode to strings
        public static string ToHexString(byte[] inArray, HexFormattingOptions options = default) => throw null;
        public static string ToHexString(byte[] inArray, int offset, int length, HexFormattingOptions options = default) => throw null;
        public static string ToHexString(ReadOnlySpan<byte> bytes, HexFormattingOptions options = default) => throw null;
    }
}

namespace System.Buffers.Text
{
    // NEW type
    public static class Hex
    {
        // Decode
        public static OperationStatus DecodeFromUtf8(ReadOnlySpan<byte> utf8, Span<byte> bytes, out int bytesConsumed, out int bytesWritten, bool isFinalBlock = true) => throw null;
        public static OperationStatus DecodeFromUtf8InPlace(Span<byte> buffer, out int bytesWritten) => throw null;
        
        // Encode
        public static OperationStatus EncodeToUtf8(ReadOnlySpan<byte> bytes, Span<byte> utf8, out int bytesConsumed, out int bytesWritten, bool isFinalBlock = true) => throw null;
        public static OperationStatus EncodeToUtf8InPlace(Span<byte> buffer, int dataLength, out int bytesWritten) => throw null;
    }
}