Extends Yoast schema to add event data

yoast-schema.php

<?php

include ("classes/Schema_Event.php");

add_filter( 'wpseo_schema_graph_pieces', 'PREFIX_add_graph_pieces', 11, 2 );

/**
 * Adds Schema pieces to our output.
 *
 * @param array                 $pieces  Graph pieces to output.
 * @param \WPSEO_Schema_Context $context Object with context variables.
 *
 * @return array $pieces Graph pieces to output.
 */
function PREFIX_add_graph_pieces( $pieces, $context ) {
    $pieces[] = new Schema_Event( $context );
    return $pieces;
}