Modify the available block formats within WordPress' TinyMCE editor. A quick solution for https://twitter.com/cdils/status/970854979735977984

## cdils.php
<?php

/**
 * Change the block formats available in TinyMCE.
 *
 * @link http://codex.wordpress.org/TinyMCE_Custom_Styles
 *
 * @param array $init Default settings to be overridden.
 *
 * @return array The modified $init array.
 */
function cdils_change_mce_block_formats( $init ) {
	$block_formats = array(
		'Paragraph=p',
		'Heading 1=h1',
		'Heading 2=h2',
		'Heading 3=h3',
		'Heading 4=h4',
		'Heading 5=h5',
		'Heading 6=h6',
		'Preformatted=pre',
		'Code=code',
	);
	$init['block_formats'] = implode( ';', $block_formats );

	return $init;
}
add_filter( 'tiny_mce_before_init', 'cdils_change_mce_block_formats' );