func NewClosure(c *Code) *Closure {
	return &Closure{
		Code:     c,
		Upvalues: make([]Cell, c.UpvalueCount),
	}
}
NewClosure returns a pointer to a new Closure instance for the given code.
package runtime
type Closure struct {
	*Code
	Upvalues     []Cell
	upvalueIndex int
}