The file has been corrupted or is not a valid notebook file. 
SyntaxError: Expected ',' or ']' after array element in JSON at position 40870 (line 748 column 1)
CustomError: SyntaxError: Expected ',' or ']' after array element in JSON at position 40870 (line 748 column 1)
    at new qM (https://ssl.gstatic.com/colaboratory-static/common/8e5fae8429764217c8c60f7f0fea86be/external_binary.js:2441:164)
    at va.program_ (https://ssl.gstatic.com/colaboratory-static/common/8e5fae8429764217c8c60f7f0fea86be/external_binary.js:2424:514)
    at ya (https://ssl.gstatic.com/colaboratory-static/common/8e5fae8429764217c8c60f7f0fea86be/external_binary.js:16:57)
    at va.next_ (https://ssl.gstatic.com/colaboratory-static/common/8e5fae8429764217c8c60f7f0fea86be/external_binary.js:14:195)
    at kaa.next (https://ssl.gstatic.com/colaboratory-static/common/8e5fae8429764217c8c60f7f0fea86be/external_binary.js:17:48)
    at b (https://ssl.gstatic.com/colaboratory-static/common/8e5fae8429764217c8c60f7f0fea86be/external_binary.js:17:309)
 OK