public function add($sHeader)
    {
        foreach ($this->headerList as $sTmp) {
            if ($sTmp == $sHeader) {
                throw new Exception("The '{$sHeader}' header has already been added.");
            }
        }
        $this->headerList[] = $sHeader;
        return self::$instance;
    }
public function add($sHeader)
    {
        foreach ($this->headerList as $sTmp) {
            if ($sTmp == $sHeader) {
                throw new Exception("The '{$sHeader}' header has already been added.");
            }
        }
        $this->headerList[] = $sHeader;
        return self::$instance;
    }
public function add ( $ sHeader ) { foreach ( $ this -> headerList as $ sTmp ) { if ( $ sTmp == $ sHeader ) { throw new Exception ( "The '{$sHeader}' header has already been added." ) ; } } $ this -> headerList [ ] = $ sHeader ; return self :: $ instance ; }
It adds the header to the stack.
@param string $sHeader The page header.
@return self.
@throws \core\Exception It throws if passed header was already added earlier.
It adds the header to the stack .