rainbow.cpp:4:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
4 | main(){
| ^~~~
/usr/bin/ld: /tmp/ccvtadxF.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccutJCUE.o:rainbow.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccvtadxF.o: in function `main':
grader.cpp:(.text.startup+0xed): undefined reference to `init(int, int, int, int, int, char*)'
/usr/bin/ld: grader.cpp:(.text.startup+0x167): undefined reference to `colour(int, int, int, int)'
collect2: error: ld returned 1 exit status