SSD1306 Connection troubles

Looks like it's already at the correct address - '0x3C' (in the module) is half '0x78' - there's usually a bit of confusion about I2C addresses (whether they're between 0 and 127, or 0 and 254 - and always even).

Do you get any errors displayed? If you don't have the correct address then there should be errors displayed on the console. Otherwise either:

• The data is going into the display, but for some reason (power supply, or maybe the initialisation code is different for your display) it's not being displayed.
  
• The code isn't being executed at all - it might be worth adding console.log("Hello") right by g.flip() to make sure it's actually executing.