lib/Http/Response.php
public function setHeader($key, $value)
    {
        $this->headers[strval($key)] = strval($value);
        return $this;
    }
public function setHeader($key, $value)
    {
        $this->headers[strval($key)] = strval($value);
        return $this;
    }
public function setHeader ( $ key , $ value ) { $ this -> headers [ strval ( $ key ) ] = strval ( $ value ) ; return $ this ; }
Sets a HTTP header to a certain value.

@param string $key
@param string $value
@return $this
Sets a HTTP header to a certain value .