This module provides access to the GPIO (General Purpose I/O) subsystem.
All access is based on the I/O index number on the NodeMCU dev kits, not the internal gpio pin. For example, the D0 pin on the dev kit is mapped to the internal GPIO pin 16.
If not using a NodeMCU dev kit, please refer to the below GPIO pin maps for the index<->gpio mapping.
| IO index | ESP8266 pin | IO index | ESP8266 pin |