esp32_cam_webserver:undefined reference

I am getting the following error when compiling esp32_cam_webserver. I don't know what I'm missing? I am a newbie. Any advice is greatly appreciated!

C:\Users\yoy\AppData\Local\Temp\arduino_build_333887\sketch\esp32_cam_webserver.ino.cpp.o:(.literal._Z5setupv+0x64): undefined reference to'parseBytes(char const*, char, unsigned char*, int, int)'
C:\Users\yoy\AppData\Local\Temp\arduino_build_333887\sketch\esp32_cam_webserver.ino.cpp.o: In function 'setup()':
c:\Users\yoy\Desktop\esp32\esp32_cam_webserver/esp32_cam_webserver.ino:175: undefined reference to 'parseBytes(char const*, char, unsigned char*, int, int)'
collect2.exe: error: ld returned 1 exit status