Info on shop_isle_loop_post hook

I’m trying to understand how to customize the search page and I’m testing to to see if I can use the shop_isle_loop_post hook to print a simple “Hello World” literal string. But it is not working. I tried adding this to the end of my functions.php file.

/* EHW - 2018.11.19 - Loop post */
function ehw_test(){
echo "<div style='background:yellow;'>AWESOME!</div>";
}
add_action('shop_isle_loop_post','ehw_test');

What I expected to see was a yellow div that said “AWESOME!” after every post in my blog. But, instead I’m seeing nothing.

1. Where can I find the documentation that details the purpose and usage of the shop_isle_loop_post hook?

2. Why isn’t my echo statement working?

Thanks.

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