docs: def ToByteArray(self):
      """Serialize the command.
  
      Encodes the command as per the U2F specs, using the standard
      ISO 7816-4 extended encoding.  All Commands expect data, so
      Le is always present.
  
      Returns:
        Python bytearray of the encoded command.
      """
      lc = self.InternalEncodeLc()
      out = bytearray(4)  # will extend
  
      out[0] = self.cla
      out[1] = self.ins
      out[2] = self.p1
      out[3] = self.p2
      if self.data:
        out.extend(lc)
        out.extend(self.data)
        out.extend([0x00, 0x00])  # Le
      else:
        out.extend([0x00, 0x00, 0x00])  # Le
      return out