On the _php skill of <<< operator in PHP

PHP provides a way for the <<< operator to build multiple-line string sequences, often referred to as here-document or shorthand for heredoc.

This method details the literal value of the string and retains the underline and other spaces (including indentation) of the string in the text. For example:

<?php
$author = ' Wixy ';
echo <<<_end
thisis a headline
thisis.
Thisis the second line.
---writtenby $author.
_end;
? >

The PHP parser outputs all content in the middle of two _end tags, equivalent to a string quoted in double quotes.
This means that we can write an entire HTML language directly in the PHP code, and then use PHP variables to replace the specific dynamic parts.

 <?php
 $out =<<<_end ...
 _end;
 ? >

You can also assign the contents of two tags to variables in this way.

Note: The _end tag used to close must be placed on a single line, and no additional content can be added to the line, even if the annotation or space is not allowed