title: openpyxl does not work error if I use the filepath from the os module
body: <p>Hi everyone I am trying to extract data from a list of spreadsheets on a folder using python with openpyxl and the os module. I retrieve the list of file, get the path from them and use it to load the workbook but each time the path trigger an error as each backslash is doubled, so if my file is on c:\Users\me\myfile it ends as C:\Users\me\myfile</p>
  <p>here is the code I used</p>
  <p>import os
  from openpyxl import Workbook,load_workbook</p>
  <p>mydir = r'C:\Users\me\PycharmProjects\</p>
  <p>for file in os.listdir(mydir):</p>
  <pre><code>if file.endswith('.xlsx'):
      filepath = os.path.abspath(file)
      wb = load_workbook(filepath, read_only=True)
      print(wb.sheetnames)
  </code></pre>