You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: blackriper.go
    path of file: ./repos/retos-programacion-2023/Retos/Reto #32 - LA COLUMNA DE EXCEL [Media]/go
    
    the code of the file until where you have to start completion: package main

import (
	"fmt"
	"strings"
)

// definimos metodos de trabajo
type Cell interface {
	ReadData()
	GetValueColum()
}

// implementacion de los metodos de trabajo
type Excel struct {
	Colum string
}

// leer
    
func (e *Excel) GetValueColum() {
	var finalValue int
	switch {
	case len(e.Colum) == 1:
		finalValue = ValueOneLetter(e.Colum)
	case len(e.Colum) == 2:
		finalValue = ValueTwoLetters(e.Colum)
	case len(e.Colum) == 3:
		finalValue = ValueThreeLetters(e.Colum)
	}
	fmt.Printf("the value of column %v is %v ", e.Colum, finalValue)
}