How to add new methods to existing types in Go? (e.g., to int or string)

Hi everyone! I just started learning Go after Python and C#, and I'm having trouble extending the functionality of built-in types. In Python I used to do this: ```python # Python - monkey patching class MyInt(int): def is_even(self): return self % 2 == 0 print(MyInt(4).is_even()) # True ``` In C# there are extension methods: ```csharp // C# Extension Method public static class IntExtensions { public static bool IsEven(this int value) { return value % 2 == 0; } } ``` Now I'm trying to do the same in Go. I want to add an `IsEven()` method to the `int` type to check if a number is even. Here's what I'm trying: ```go package main import "fmt" // Trying to extend int func (i int) IsEven() bool { return i%2 == 0 } ```