Get gravatar img src in non-WP context

gravatar.php

<?php

function gravatar_img_src() {

	$emails = array();

  # Gravatar is all about dem jpg's
	$file_extension = '.jpg';
	# add a size via query here, eg 250, 400
	$file_size 		 = '?size=250px';
  
  # then just md5 the email
	foreach ( $emails as $email ) {
		echo 'https://secure.gravatar.com/avatar/' . md5( $email ) . $file_extension . $file_size . PHP_EOL;
	}
}

gravatar_img_src();