我的 IF 语句出现语法错误，不知道为什么？

我正在尝试在 python 3.7 中运行以下代码。我不断收到无效的语法错误，但不知道为什么，有人能发现我做错了什么吗？缩进似乎没问题，我相信我的“打印”在正确的括号中，但我完全迷失在“if”和“else”语句中。

class pdfPositionHandling:

    def parse_obj(self, lt_objs):

        # loop over the object list
        for obj in lt_objs:

            if isinstance(obj, pdfminer.layout.LTTextLine):
                print ("%6d, %6d, %s" % (obj.bbox[0], obj.bbox[1], obj.get_text().replace('\n', '_'))

            # if it's a textbox, also recurse
            if isinstance(obj, pdfminer.layout.LTTextBoxHorizontal):
                self.parse_obj(obj._objs)

            # if it's a container, recurse
            elif isinstance(obj, pdfminer.layout.LTFigure):
                self.parse_obj(obj._objs)

    def parsepdf(self, filename, startpage, endpage):

        # Open a PDF file.
        fp = open(filename, 'rb')

        # Create a PDF parser object associated with the file object.
        parser = PDFParser(fp)

        # Create a PDF document object that stores the document structure.
        # Password for initialization as 2nd parameter
        document = PDFDocument(parser)

        # Check if the document allows text extraction. If not, abort.
        if not document.is_extractable:
            raise PDFTextExtractionNotAllowed

        # Create a PDF resource manager object that stores shared resources.
        rsrcmgr = PDFResourceManager()

        # Create a PDF device object.
        device = PDFDevice(rsrcmgr)

        # BEGIN LAYOUT ANALYSIS
        # Set parameters for analysis.
        laparams = LAParams()

        # Create a PDF page aggregator object.
        device = PDFPageAggregator(rsrcmgr, laparams=laparams)

            # Create a PDF interpreter object.
        interpreter = PDFPageInterpreter(rsrcmgr, device)


        i = 0
        # loop over all pages in the document
        for page in PDFPage.create_pages(document):
            if i >= startpage and i <= endpage:
                # read the page into a layout object
                interpreter.process_page(page)
                layout = device.get_result()

                # extract text from this object
                self.parse_obj(layout._objs)
            i += 1

我收到以下错误：

File "C:/Users/951298/Documents/Python Scripts/PDF Scraping/untitled1.py", line 12
    if isinstance(obj, pdfminer.layout.LTTextBoxHorizontal):
                                                           ^
SyntaxError: invalid syntax

不知道为什么它最后指向冒号？