func String(v interface{}) string {
	if v1, ok := v.(string); ok {
		return v1
	}
	return ""
}
// String returns string value of v if v is a
// string, or "" otherwise.
String returns string value of v if v is a
string, or "" otherwise.
// String returns string value of v if v is a // string or " " otherwise .
func String(v interface{}) string {
	if v1, ok := v.(string); ok {
		return v1
	}
	return ""
}
func String ( v interface { } ) string { if v1 , ok := v . ( string ) ; ok { return v1 } return " " }
String returns string value of v if v is a
string, or "" otherwise.
String returns string value of v if v is a string or " " otherwise .