framework/web/HeaderCollection.php
public function set($name, $value = '')
    {
        $name = strtolower($name);
        $this->_headers[$name] = (array) $value;

        return $this;
    }
public function set($name, $value = '')
    {
        $name = strtolower($name);
        $this->_headers[$name] = (array) $value;

        return $this;
    }
public function set ( $ name , $ value = '' ) { $ name = strtolower ( $ name ) ; $ this -> _headers [ $ name ] = ( array ) $ value ; return $ this ; }
Adds a new header.
If there is already a header with the same name, it will be replaced.
@param string $name the name of the header
@param string $value the value of the header
@return $this the collection object itself
Adds a new header . If there is already a header with the same name it will be replaced .