src/includes/traits/OverloadMembers.php
public function __isset(string $property): bool
    {
        if (!isset($property[1]) && ($property === 'c' || $property === 's' || $property === 'a' || $property === 'f')) {
            // NOTE: `f` comes last here, because it improves the speed at which a match occurs.
            return true; // Public read-only access.
        } else {
            return isset($this->x___overload_data[$property]);
        }
    }
public function __isset(string $property): bool
    {
        if (!isset($property[1]) && ($property === 'c' || $property === 's' || $property === 'a' || $property === 'f')) {
            // NOTE: `f` comes last here, because it improves the speed at which a match occurs.
            return true; // Public read-only access.
        } else {
            return isset($this->x___overload_data[$property]);
        }
    }
Magic/overload checker.

@since 150424 Initial release.

@param string $property Property key.

@return bool True if non-null.