How to get ESP8266 Wifi MAC ?

running Espruino on ESP8266, like esptool.py does:

esptool.py --port /dev/cu.usbserial --baud 115200 read_mac

Connecting...
MAC: 18:fe:34:05:99:c9

inside esptool.py

// OTP ROM addresses
    ESP_OTP_MAC0    = 0x3ff00050
    ESP_OTP_MAC1    = 0x3ff00054

def read_mac(self):
        mac0 = self.read_reg(self.ESP_OTP_MAC0)
        mac1 = self.read_reg(self.ESP_OTP_MAC1)
        if ((mac1 >> 16) & 0xff) == 0:
            oui = (0x18, 0xfe, 0x34)
        elif ((mac1 >> 16) & 0xff) == 1:
            oui = (0xac, 0xd0, 0x74)
        else:
            raise FatalError("Unknown OUI")
        return oui + ((mac1 >> 8) & 0xff, mac1 & 0xff, (mac0 >> 24) & 0xff)