func GoVersion(ctx context.Context, inv Invocation, r *Runner) (int, error) {
	inv.Verb = "list"
	inv.Args = []string{"-e", "-f", `{{context.ReleaseTags}}`}
	inv.Env = append(append([]string{}, inv.Env...), "GO111MODULE=off")
	inv.ModFile = ""
	inv.ModFlag = ""
	stdoutBytes, err := r.Run(ctx, inv)
	if err != nil {
		return 0, err
	}
	stdout := stdoutBytes.String()
	if len(stdout) < 3 {
		return 0, fmt.Errorf("bad ReleaseTags output: %q", stdout)
	}
	tags := strings.Fields(stdout[1 : len(stdout)-2])
	for i := len(tags) - 1; i >= 0; i-- {
		var version int
		if _, err := fmt.Sscanf(tags[i], "go1.%d", &version); err != nil {
			continue
		}
		return version, nil
	}
	return 0, fmt.Errorf("no parseable ReleaseTags in %v", tags)
}
GoVersion checks the go version by running "go list" with modules off.
It returns the X in Go 1.X.
package gocommand
import (
	"context"
	"fmt"
	"strings"
)