Code by Josh#5514 - Tue Aug 06 2019 14:07:18 GMT+0000 (Coordinated Universal Time)

CodeBlockPaste.cpp

#include <Wire.h>

void setup() {
 Serial.begin(9600); /* begin serial for debug /
 Wire.begin(D1, D2); / join i2c bus with SDA=D1 and SCL=D2 of NodeMCU /
}

void loop() {
 Wire.beginTransmission(8); / begin with device address 8 /
 Wire.write("Hello Arduino");  / sends hello string /
 Wire.endTransmission();    / stop transmitting /

 Wire.requestFrom(8, 13); / request & read data of size 13 from slave /
 while(Wire.available()){
    char c = Wire.read();
    Serial.print(c, HEX);
    Serial.println();
 }
 Serial.println();
 delay(1000);
}
leonardo's code
'''#include <Wire.h>

void setup() {
 Wire.begin(8);                / join i2c bus with address 8 /
 Wire.onReceive(receiveEvent); / register receive event /
 Wire.onRequest(requestEvent); / register request event /
 Serial.begin(9600);           / start serial for debug /
}

void loop() {
 delay(100);