Plugin won’t read my code.

I really like the concept of this plugin but I’m having issues getting it to save without an error. I run my PHP code through multiple test sites and they say it is fine but when I load it into the plugin and try to save, I keep getting a error near the bottom . I’m running PHP 7.3. Here is my code:

$currentpage = $_SERVER[‘REQUEST_URI’];
if(“/page-6/”==$currentpage) {
function mytheme_custom_excerpt_length( $length ){
return 30;
}
} elseif (“/page-5/”==$currentpage) {
echo “Have Good”;
function mytheme_custom_excerpt_length( $length ) {
return 10;
}
} elseif (“/page-4/”==$currentpage) {
echo “Have Good”;
function mytheme_custom_excerpt_length( $length ) {
return 10;

}
}

add_filter( ‘excerpt_length’, ‘mytheme_custom_excerpt_length’, 999 );