barchart.go
func (b *BarChart) AddData(val BarData) {
	b.mtx.Lock()
	defer b.mtx.Unlock()

	b.data = append(b.data, val)
}
func (b *BarChart) AddData(val BarData) {
	b.mtx.Lock()
	defer b.mtx.Unlock()

	b.data = append(b.data, val)
}
// AddData appends a new bar to a chart