code: public function getAppCode($path, $width = 430, $autoColor = false, $lineColor = ['r' => 0, 'g' => 0, 'b' => 0])
      {
          $params = [
              'path' => $path,
              'width' => $width,
              'auto_color' => $autoColor,
              'line_color' => $lineColor,
          ];
  
          return $this->getStream(self::API_GET_WXACODE, $params);
      }
docs: Get WXACode.
  
  @param string $path
  @param int    $width
  @param bool   $autoColor
  @param array  $lineColor
  
  @return \Psr\Http\Message\StreamInterface