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: col.go
    path of file: ./repos/go-gin-example/vendor/github.com/360EntSecGroup-Skylar/excelize
    
    the code of the file until where you have to start completion: package excelize

import (
	"bytes"
	"math"
	"strconv"
	"strings"
)

// Define the default cell size and EMU unit of measurement.
const (
	defaultColWidthPixels  float64 = 64
	defaultRowHeightPixels float64 = 20
	EMU                    int     = 9525
)

// GetColVisible provides a function to get visible of a single column by given
// worksheet name and 
    
func (f *File) SetColOutlineLevel(sheet, column string, level uint8) {
	xlsx := f.workSheetReader(sheet)
	c := TitleToNumber(strings.ToUpper(column)) + 1
	col := xlsxCol{
		Min:          c,
		Max:          c,
		OutlineLevel: level,
		CustomWidth:  true,
	}
	if xlsx.Cols == nil {
		cols := xlsxCols{}
		cols.Col = append(cols.Col, col)
		xlsx.Cols = &cols
		return
	}
	for v := range xlsx.Cols.Col {
		if xlsx.Cols.Col[v].Min <= c && c <= xlsx.Cols.Col[v].Max {
			col = xlsx.Cols.Col[v]
		}
	}
	col.Min = c
	col.Max = c
	col.OutlineLevel = level
	col.CustomWidth = true
	xlsx.Cols.Col = append(xlsx.Cols.Col, col)
}