is_bool in PHP

is_bool — Finds out whether a variable is a boolean
Syntax: bool is_bool ( mixed $var )
Finds whether the given variable is a boolean.
Parameters: 
var:The variable being evaluated.
Return Values:
Returns TRUE if var is a boolean, FALSE otherwise.
Example #1:
<?php
$a = false;
$b = 0;

// Since $a is a boolean, it will return true
if (is_bool($a) === true) {
    echo "Yes, this is a boolean";
}

// Since $b is not a boolean, it will return false
if (is_bool($b) === false) {
    echo "No, this is not a boolean";
}
?>