public function getAuthorReviews( $author, $size = SPIGET4PHP_DEFAULT, $page =  SPIGET4PHP_DEFAULT, $sort = SPIGET4PHP_DEFAULT, $fields = SPIGET4PHP_DEFAULT )
    {
        $function = 'authors/'.$author.'/reviews';
        $args = [];
        if ( !is_null( $size ) ) $args['size'] = $size;
        if ( !is_null( $page ) ) $args['page'] = $page;
        if ( !is_null( $sort ) ) $args['sort'] = $sort;
        if ( !is_null( $fields ) ) $args['fields'] = implode(',', $fields );
        return $this->getResult( $function, $args );
    }