func (s *Script) Lang(lang string) *Script {
	s.lang = lang
	return s
}
Lang sets the language of the script. Permitted values are "groovy",
"expression", "mustache", "mvel" (default), "javascript", "python".
To use certain languages, you need to configure your server and/or
add plugins. See https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-scripting.html
for details.
package elastic
import "errors"
type Script struct {
	script string
	typ    string
	lang   string
	params map[string]interface{}
}
func NewScript(script string) *Script {
	return &Script{
		script: script,
		typ:    "",  
		params: make(map[string]interface{}),
	}
}
func NewScriptInline(script string) *Script {
	return NewScript(script).Type("inline")
}
func NewScriptId(script string) *Script {
	return NewScript(script).Type("id")
}
func NewScriptFile(script string) *Script {
	return NewScript(script).Type("file")
}
func (s *Script) Script(script string) *Script {
	s.script = script
	return s
}
func (s *Script) Type(typ string) *Script {
	s.typ = typ
	return s
}