GraphQL\Validator\Rules\NoUnusedVariables::unusedVariableMessage PHP Method

    static function unusedVariableMessage($varName, $opName = null)
    {
        return $opName ? "Variable \"\${$varName}\" is never used in operation \"{$opName}\"." : "Variable \"\${$varName}\" is never used.";
    }

 private function unusedVar($varName, $line, $column)
 {
     return FormattedError::create(NoUnusedVariables::unusedVariableMessage($varName), [new SourceLocation($line, $column)]);
 }