sparkchart.go
func (b *SparkChart) SetHilitePeaks(hilite bool) {
	b.mtx.Lock()
	defer b.mtx.Unlock()

	b.hiliteMax = hilite
}
func (b *SparkChart) SetHilitePeaks(hilite bool) {
	b.mtx.Lock()
	defer b.mtx.Unlock()

	b.hiliteMax = hilite
}
// SetHilitePeaks enables or disables hiliting maximum
// values with different colors