#include <EasyButton.h>

// Arduino pin number where the button is connected.
#define BUTTON_PIN 4

// Button.
EasyButton button(BUTTON_PIN);

// Callback.
void onPressed() {
    Serial.println("Button has been pressed!");
}

void setup() {
    Serial.begin(115200);
    Serial.println("Button 00000");

    // Initialize the button.
    button.begin();

    // Attach callback.
    button.onPressed(onPressed);
}

void loop() {
    // Continuously update the button state.
    button.read();
}