Python3.x 如何解决No module named 'frontend'错误消息

我安装了PymuPDF/fitz，因为我试图从PDF文件中提取图像.然而，在运行下面的代码时，我看到了No module named 'frontend'个.

    doc = fitz.open(pdf_path)
            for i in range(len(doc)):
                for img in doc.getPageImageList(i):
                    xref = img[0]
                    pix = fitz.Pixmap(doc, xref)
                    if pix.n < 5:  # this is GRAY or RGB
                        pix.writePNG("p%s-%s.png" % (i, xref))
                    else:  # CMYK: convert to RGB first
                        pix1 = fitz.Pixmap(fitz.csRGB, pix)
                        pix1.writePNG("p%s-%s.png" % (i, xref))
                        pix1 = None
                    pix = None

我已经搜索过了，但是没有关于这种错误的报告.我已经安装了PyMuPDF、muPDF和fitz模块

以下是完整的错误:

    Traceback (most recent call last):
      File "/home/waqar/PycharmProjects/predator/ExtractFileImage.py", line 1, in <module>
        import fitz
      File "/home/waqar/anaconda3/envs/retinanet/lib/python3.6/site-packages/fitz/__init__.py", line 1, in <module>
        from frontend import *
    ModuleNotFoundError: No module named 'frontend'