Core/Html/Bootstrap/Navbar/Navbar.php
public function isCollapsible($collapsible = null)
    {
        if (isset($collapsible)) {
            $this->collapsible = (bool) $collapsible;
            return $this;
        } else {
            return $this->collapsible;
        }
    }
public function isCollapsible($collapsible = null)
    {
        if (isset($collapsible)) {
            $this->collapsible = (bool) $collapsible;
            return $this;
        } else {
            return $this->collapsible;
        }
    }
public function isCollapsible ( $ collapsible = null ) { if ( isset ( $ collapsible ) ) { $ this -> collapsible = ( bool ) $ collapsible ; return $ this ; } else { return $ this -> collapsible ; } }
Sets or gets collapsible flag.

@param bool $collapsible

@return \Core\Html\Bootstrap\Navbar\Navbar|boolean
Sets or gets collapsible flag .