code: func (d *Decoder) IsValidFile() bool {
  	d.ReadInfo()
  	if d.err != nil && d.err != io.EOF {
  		return false
  	}
  	if d.NumChans < 1 {
  		return false
  	}
  	if d.BitDepth < 8 {
  		return false
  	}
  	if d, err := d.Duration(); err != nil || d <= 0 {
  		return false
  	}
  
  	return true
  }
docs: // IsValidFile verifies that the file is valid/readable.