Can you explain the Trinitary Operator in PHP and how it can be used as a shortcut for isset() checks?

When working with PHP, we often need to check if a variable is set before using it to avoid errors. One common way to do this is by using the isset() function. However, the ternary operator (?:) can be used as a shortcut for isset() checks, making the code more concise and readable.

// Using the ternary operator as a shortcut for isset() checks
$variable = isset($_POST['variable']) ? $_POST['variable'] : 'default_value';