adding google fonts as options

Hello

I created a child theme and then created a functions php with the content below and uploaded it to the child theme but it broke the site, so I removed it and it has gone back to normal. Please let me know what I am doing wrong. I am trying to get the google fonts Gabriela https://fonts.google.com/specimen/Gabriela?selection.family=Gabriela and Fredericka the Great https://fonts.google.com/specimen/Fredericka+the+Great added to the font options in the theme options.

<?php

/* Custom code goes below this line. */

add_filter( ‘avf_google_heading_font’, ‘avia_add_heading_font’);
function avia_add_heading_font($fonts)
{
$fonts[‘Fredericka the Great’] = ‘Fredericka the Great:400,600,800’;
return $fonts;
}

add_filter( ‘avf_google_content_font’, ‘avia_add_content_font’);
function avia_add_content_font($fonts)
{
$fonts[‘Fredericka the Great’] = ‘Fredericka the Great:400,600,800’;
return $fonts;
}

add_filter( ‘avf_google_heading_font’, ‘avia_add_heading_font’);
function avia_add_heading_font($fonts)
{
$fonts[‘Gabriela’] = ‘Gabriela:400,600,800’;
return $fonts;
}

add_filter( ‘avf_google_content_font’, ‘avia_add_content_font’);
function avia_add_content_font($fonts)
{
$fonts[‘Gabriela’] = ‘Gabriela:400,600,800’;
return $fonts;
}

/* Custom code goes above this line. */
?>