'arcPing' was not declared in this scope

I’m using Nitroxleecher’s Servotor32.cpp code that I got from the Ultrasonic Distance Sensor/Module board and when I compile the arduino code, I’m getting the following error messages:

servotor32.cpp: In member function ‘void Servotor32::processChar(char)’:
servotor32.cpp:388: error: ‘arcPing’ was not declared in this scope
servotor32.cpp: At global scope:
servotor32.cpp:479: error: no ‘void Servotor32::arcPing()’ member function declared in class ‘Servotor32’

What do I need to do to fix this?