docs: def flash_spi_attach(self, hspi_arg):
          """Send SPI attach command to enable the SPI flash pins
  
          ESP8266 ROM does this when you send flash_begin, ESP32 ROM
          has it as a SPI command.
          """
          # last 3 bytes in ESP_SPI_ATTACH argument are reserved values
          arg = struct.pack('<I', hspi_arg)
          if not self.IS_STUB:
              # ESP32 ROM loader takes additional 'is legacy' arg, which is not
              # currently supported in the stub loader or esptool.py (as it's not usually needed.)
              is_legacy = 0
              arg += struct.pack('BBBB', is_legacy, 0, 0, 0)
          self.check_command("configure SPI flash pins", ESP32ROM.ESP_SPI_ATTACH, arg)