How to run:
go run main.go
Demonstration:
Enter text: grey 1
[grey 1, ]
Enter text: green 13
[grey 1, green 13, ]
Enter text: red 1
invalid input, available values: grey, black, green, purple
Enter text: grey 15
invalid input, available values: 1-13
Enter text: purple 8
[grey 1, green 13, purple 8, ]