func (f *File) GetColOutlineLevel(sheet, column string) uint8 {
	xlsx := f.workSheetReader(sheet)
	col := TitleToNumber(strings.ToUpper(column)) + 1
	level := uint8(0)
	if xlsx.Cols == nil {
		return level
	}
	for c := range xlsx.Cols.Col {
		if xlsx.Cols.Col[c].Min <= col && col <= xlsx.Cols.Col[c].Max {
			level = xlsx.Cols.Col[c].OutlineLevel
		}
	}
	return level
}
GetColOutlineLevel provides a function to get outline level of a single
column by given worksheet name and column name. For example, get outline
level of column D in Sheet1:

xlsx.GetColOutlineLevel("Sheet1", "D")
package excelize
import (
	"bytes"
	"math"
	"strconv"
	"strings"
)
const (
	defaultColWidthPixels  float64 = 64
	defaultRowHeightPixels float64 = 20
	EMU                    int     = 9525
)
func (f *File) GetColVisible(sheet, column string) bool {
	xlsx := f.workSheetReader(sheet)
	col := TitleToNumber(strings.ToUpper(column)) + 1
	visible := true
	if xlsx.Cols == nil {
		return visible
	}
	for c := range xlsx.Cols.Col {
		if xlsx.Cols.Col[c].Min <= col && col <= xlsx.Cols.Col[c].Max {
			visible = !xlsx.Cols.Col[c].Hidden
		}
	}
	return visible
}
func (f *File) SetColVisible(sheet, column string, visible bool) {
	xlsx := f.workSheetReader(sheet)
	c := TitleToNumber(strings.ToUpper(column)) + 1
	col := xlsxCol{
		Min:         c,
		Max:         c,
		Hidden:      !visible,
		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.Hidden = !visible
	col.CustomWidth = true
	xlsx.Cols.Col = append(xlsx.Cols.Col, col)
}