code: func (o *Osc) SetAttackInMs(ms int) {
  	if o == nil {
  		return
  	}
  	if ms <= 0 {
  		o.attackInSamples = 0
  		return
  	}
  	o.attackInSamples = int(float32(o.Fs) / (1000.0 / float32(ms)))
  }
docs: // SetAttackInMs sets the duration for the oscillator to be at full amplitude
  // after it starts.