func NewOptionalType(element Type) Type {
	if isTypeOptional(element) {
		return element
	}
	return &OptionalType{element}
}
NewOptionalType creates a new optional type that may or may not have the specified 'element' type
package astmodel
import (
	"fmt"
	"strings"
	"github.com/dave/dst"
)
type OptionalType struct {
	element Type
}
var _ Type = &OptionalType{}
var _ MetaType = &OptionalType{}