public function isHeaderSent(&$file = null, &$line = null)
    {
        return $this->unitTest ? (bool)$this->sentHeaders : headers_sent($file, $line);
    }
public function isHeaderSent(&$file = null, &$line = null)
    {
        return $this->unitTest ? (bool)$this->sentHeaders : headers_sent($file, $line);
    }
public function isHeaderSent ( & $ file = null , & $ line = null ) { return $ this -> unitTest ? ( bool ) $ this -> sentHeaders : headers_sent ( $ file , $ line ) ; }
Checks if or where headers have been sent

If NOT in unit test mode and the optional `file` and `line` parameters
are set, `isHeaderSent()` will put the PHP source file name and line
number where output started in the file and line variables

@param string $file
@param int $line The line number where the output started
@return bool
@link http://php.net/manual/en/function.headers-sent.php
Checks if or where headers have been sent