gistfile1.txt

MyBase: class {
    .some_method: (a) {
        return a + 2
    }
}

MyObject: class {
    .prototype: MyBase

    // Method 1
    .old_some_method: .some_method
    .some_method: (a) {
        return .old_some_method(a) + 2
    }

    // Method 2
    .some_method: (a) {
        old: .prototype.&some_method
        return old(a) + 2
    }
}

// Monkeypatch it!
old: MyObject.&some_method
MyObject.some_method: (a) {
    old(a)
}