Checks if the object is of this class or has this class as one of its parents
is_a ( mixed $object , string $class_name [, bool $allow_string = FALSE ] ) : bool
A class name or an object instance.
The class name
If this parameter set to FALSE, string class name as object is not allowed. This also prevents from calling autoloader if the class doesn't exist.
Returns TRUE if the object is of this class or has this class as one of its parents, FALSE otherwise.
ALLOW_STRING | FALSE
ALLOW_STRING | TRUE