/// <summary>Serializes a <see cref="FileInfo" /> by its full path as a string.</summary>
public class FileInfoFormatter<T> : IMessagePackFormatter<FileInfo>
{
    public void Serialize(
      ref MessagePackWriter writer, FileInfo value, MessagePackSerializerOptions options)
    {
        if (value == null)
        {
            writer.WriteNil();
            return;
        }

        writer.WriteString(value.FullName);
    }

    public FileInfo Deserialize(
      ref MessagePackReader reader, MessagePackSerializerOptions options)
    {
        if (reader.TryReadNil())
        {
            return null;
        }

        options.Security.DepthStep(ref reader);

        var path = reader.ReadString();

        reader.Depth--;
        return new FileInfo(path);
    }
}

public class MySpecialObjectFormatter<T> : IMessagePackFormatter<MySpecialObject>
{
    public void Serialize(
      ref MessagePackWriter writer, MySpecialObject value, MessagePackSerializerOptions options)
    {
        if (value == null)
        {
            writer.WriteNil();
            return;
        }

        writer.WriteArrayHeader(2);
        writer.WriteString(value.FullName);
        writer.WriteString(value.Age);
    }

    public MySpecialObject Deserialize(
      ref MessagePackReader reader, MessagePackSerializerOptions options)
    {
        if (reader.TryReadNil())
        {
            return null;
        }

        options.Security.DepthStep(ref reader);

        string fullName = null;
        int age = 0;

        // Loop over *all* array elements independently of how many we expect,
        // since if we're serializing an older/newer version of this object it might
        // vary in number of elements that were serialized, but the contract of the formatter
        // is that exactly one data structure must be read, regardless.
        // Alternatively, we could check that the size of the array/map is what we expect
        // and throw if it is not.
        int count = reader.ReadArrayHeader();
        for (int i = 0; i < count; i++)
        {
            case 0:
                fullName = reader.ReadString();
                break;
            case 1:
                age = reader.ReadInt32();
                break;
            default:
                reader.Skip();
                break;
        }

        reader.Depth--;
        return new MySpecialObject(fullName, age);
    }
}

        // If target type is generics, use MakeGenericType.
        if (t.IsGeneric && t.GetGenericTypeDefinition() == typeof(ValueTuple<,>))
        {
            return Activator.CreateInstance(typeof(ValueTupleFormatter<,>).MakeGenericType(t.GenericTypeArguments));
        }