code: func (f FrameHeader) IsValid() bool {
  	const sync = 0xffe00000
  	if (f & sync) != sync {
  		return false
  	}
  	if f.ID() == consts.VersionReserved {
  		return false
  	}
  	if f.BitrateIndex() == 15 {
  		return false
  	}
  	if f.SamplingFrequency() == consts.SamplingFrequencyReserved {
  		return false
  	}
  	if f.Layer() == consts.LayerReserved {
  		return false
  	}
  	if f.Emphasis() == 2 {
  		return false
  	}
  	return true
  }
docs: // IsValid returns a boolean value indicating whether the header is valid or not.