public function header($name, $value=null) 
    {
        if (is_array($name)) {
            $this->def['header'] = array_merge($this->def['header'], $name);
        } else {
            $this->def['header'][$name] = $value;
        }
        return $this;
    }
public function header($name, $value=null) 
    {
        if (is_array($name)) {
            $this->def['header'] = array_merge($this->def['header'], $name);
        } else {
            $this->def['header'][$name] = $value;
        }
        return $this;
    }
public function header ( $ name , $ value = null ) { if ( is_array ( $ name ) ) { $ this -> def [ 'header' ] = array_merge ( $ this -> def [ 'header' ] , $ name ) ; } else { $ this -> def [ 'header' ] [ $ name ] = $ value ; } return $ this ; }
set request header
@param  string $name
@param  mixed  $value
@return static
set request header