.
     *
     * @param string $str
     *
     * @return void
     */
    private function debug($str)
    {
        $str = $this->stamp($str);
        $this->log($str);
        if ($this->debug) {
            if ('cli' !== PHP_SAPI) {
                $str = '
' . htmlspecialchars($str) . '
';
            }
            echo "\n" . $str;
        }
    }

    /**
     * Adds a message to the log array
     *
     * @param string $msg
     *
     * @return void
     */
    private function log($msg)
    {
        $this->log[] = $msg;
    }

    /**
     * Prepends the given $msg with the current date and time inside square brackets.
     *
     * @param string $msg
     *
     * @return string
     */
    private function stamp($msg)
    {
        $date = \DateTime::createFromFormat('U.u', sprintf('%.f', microtime(true)))->format('Y-m-d\TH:i:s.uO');
        $line = '[' . $date . '] ' . $msg;

        return $line;
    }

    /**
     * Returns the log array
     *
     * @return array
     */
    public function getLog()
    {
        return $this->log;
    }

    /**
     * Truncates the log array
     *
     * @return void
     */
    public function clearLog()
    {
        $this->log = [];
    }

    /**
     * Compat for old lower_cased method calls.
     *
     * @param string $name
     * @param array  $args
     *
     * @return void
     */
    public function __call($name, $args)
    {
        $camelized = self::camelize($name);
        if (\method_exists($this, $camelized)) {
            return \call_user_func_array([$this, $camelized], $args);
        } else {
            trigger_error('Fatal error: Call to undefined method ' . self::class . '::' . $name . '()', E_USER_ERROR);
        }
    }

    /**
     * Set the desired connect timeout.
     *
     * @param int $timeout Connect timeout in seconds
     *
     * @return void
     */
    public function setConnectTimeout($timeout)
    {
        $this->connect_timeout = (int) $timeout;
    }

    /**
     * Get the current connect timeout.
     *
     * @return int
     */
    public function getConnectTimeout()
    {
        return $this->connect_timeout;
    }

    /**
     * Set connect port.
     *
     * @param int $port
     *
     * @return void
     */
    public function setConnectPort($port)
    {
        $this->connect_port = (int) $port;
    }

    /**
     * Get current connect port.
     *
     * @return int
     */
    public function getConnectPort()
    {
        return $this->connect_port;
    }

    /**
     * Turn on "catch-all" detection.
     *
     * @return void
     */
    public function enableCatchAllTest()
    {
        $this->catchall_test = true;
    }

    /**
     * Turn off "catch-all" detection.
     *
     * @return void
     */
    public function disableCatchAllTest()
    {
        $this->catchall_test = false;
    }

    /**
     * Returns whether "catch-all" test is to be performed or not.
     *
     * @return bool
     */
    public function isCatchAllEnabled()
    {
        return $this->catchall_test;
    }

    /**
     * Set whether "catch-all" results are considered valid or not.
     *
     * @param bool $flag When true, "catch-all" accounts are considered valid
     *
     * @return void
     */
    public function setCatchAllValidity($flag)
    {
        $this->catchall_is_valid = (bool) $flag;
    }

    /**
     * Get current state of "catch-all" validity flag.
     *
     * @return bool
     */
    public function getCatchAllValidity()
    {
        return $this->catchall_is_valid;
    }

    /**
     * Camelizes a string.
     *
     * @param string $id A string to camelize
     *
     * @return string The camelized string
     */
    private static function camelize($id)
    {
        return strtr(
            ucwords(
                strtr(
                    $id,
                    ['_' => ' ', '.' => '_ ', '\\' => '_ ']
                )
            ),
            [' ' => '']
        );
    }
}