如何在python pdfminer3k中解决此警告？

Question

当我在pythonidle中运行这些代码时，我得到了一个警告，如何解决这个问题？在

WARNING:root:Cannot locate objid= nnn

# -*- coding: utf-8 -*- 
from pdfminer.pdfinterp import PDFResourceManager, process_pdf
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from io import StringIO
from io import open

def readPDF(pdfFile):
    rsrcmgr = PDFResourceManager()
    retstr = StringIO()
    laparams = LAParams()
    device = TextConverter(rsrcmgr, retstr, laparams=laparams)

    process_pdf(rsrcmgr, device, pdfFile)
    device.close()

    content = retstr.getvalue()
    retstr.close()
    return content


def saveTxt(txt):
    with open("xxx.txt", "w",encoding="utf-8") as f:
        f.write(txt)


txt = readPDF(open('xxx.pdf', 'rb'))
saveTxt(txt)

当我将STRICT = True添加到psparser.py然后运行程序，它会返回如下：

^{pr2}$

于16:46 GTM+08 2018/06/08添加