public function from($username, $icon = null)
    {
        $this->username = $username;

        if (! is_null($icon)) {
            $this->icon = $icon;
        }

        return $this;
    }
public function from($username, $icon = null)
    {
        $this->username = $username;

        if (! is_null($icon)) {
            $this->icon = $icon;
        }

        return $this;
    }
public function from ( $ username , $ icon = null ) { $ this -> username = $ username ; if ( ! is_null ( $ icon ) ) { $ this -> icon = $ icon ; } return $ this ; }
Set a custom username and optional emoji icon for the Slack message.

@param  string  $username
@param  string|null  $icon
@return $this
Set a custom username and optional emoji icon for the Slack message .