public function clear($key = null) {
        if (is_null($key)) {
            $this->vars = array();
        }
        else {
            unset($this->vars[$key]);
        }
    }
public function clear($key = null) {
        if (is_null($key)) {
            $this->vars = array();
        }
        else {
            unset($this->vars[$key]);
        }
    }
public function clear ( $ key = null ) { if ( is_null ( $ key ) ) { $ this -> vars = array ( ) ; } else { unset ( $ this -> vars [ $ key ] ) ; } }
Unsets a variable. If no key is passed in, clear all variables.

@param string $key Key
Unsets a variable . If no key is passed in clear all variables .