go mod init chan4lk/hello
go mod tidy
GOOS=darwin GOARCH=amd64 go build -o Chapter_1-mac
GOOS=windows GOARCH=amd64 go build -o Chapter_1-windows.exe
GOOS=linux GOARCH=amd64 go build -o Chapter_1-linux
go mod init chan4lk/hello
go mod tidy
GOOS=darwin GOARCH=amd64 go build -o Chapter_1-mac
GOOS=windows GOARCH=amd64 go build -o Chapter_1-windows.exe
GOOS=linux GOARCH=amd64 go build -o Chapter_1-linux