function getErrors($purge = false, $level = false)
    {
        if (!$purge) {
            if ($level) {
                if (!isset($this->_errorsByLevel[$level])) {
                    return array();
                } else {
                    return $this->_errorsByLevel[$level];
                }
            } else {
                return $this->_errors;
            }
        }
        if ($level) {
            $ret = $this->_errorsByLevel[$level];
            foreach ($this->_errorsByLevel[$level] as $i => $unused) {
                // entries are references to the $_errors array
                $this->_errorsByLevel[$level][$i] = false;
            }
            // array_filter removes all entries === false
            $this->_errors = array_filter($this->_errors);
            unset($this->_errorsByLevel[$level]);
            return $ret;
        }
        $ret = $this->_errors;
        $this->_errors = array();
        $this->_errorsByLevel = array();
        return $ret;
    }