public function mutate(Node $node)
    {
        return new Node\Expr\BinaryOp\Minus($node->left, $node->right, $node->getAttributes());
    }
public function mutate(Node $node)
    {
        return new Node\Expr\BinaryOp\Minus($node->left, $node->right, $node->getAttributes());
    }
public function mutate ( Node $ node ) { return new Node \ Expr \ BinaryOp \ Minus ( $ node -> left , $ node -> right , $ node -> getAttributes ( ) ) ; }
Replaces "+" with "-"

@return Node\Expr\BinaryOp\Minus
Replaces + with -