func (g Group) Go(f func() error) {
	g.wrapped.Go(f)
}
Go calls the given function in a new goroutine.
package ctxgroup
import (
	"context"
	"golang.org/x/sync/errgroup"
)
type Group struct {
	wrapped *errgroup.Group
	ctx     context.Context
}
func (g Group) Wait() error {
	ctxErr := g.ctx.Err()
	err := g.wrapped.Wait()
	if err != nil {
		return err
	}
	return ctxErr
}
func WithContext(ctx context.Context) Group {
	grp, ctx := errgroup.WithContext(ctx)
	return Group{
		wrapped: grp,
		ctx:     ctx,
	}
}