Obtaining MAC address

I am using the Sparkfun WiFi Shield for the Arduino. The header files I’m using are SparkFunESP8266WiFi.h and SoftwareSerial.h. I am trying to get the MAC address for the device. The code I am using is:

int myMAC = esp8266.localMAC();

Serial.print(F("MAC Address: "));

Serial.println(myMAC);

This gives an error.

What is the correct coding to get the MAC?

What is the error?