code: func (d *DirectPinDriver) DigitalRead() (val int, err error) {
  	if reader, ok := d.Connection().(DigitalReader); ok {
  		return reader.DigitalRead(d.Pin())
  	}
  	err = ErrDigitalReadUnsupported
  	return
  }
docs: // DigitalRead returns the current digital state of the pin