python解决方案：WindowsError: [Error 2]

def renameFile(filename):
  filePre = "D:\\FileDemo\\Python\\pt.py"
  os.rename(filePre, filename)
  print os.listdir(filePre)

if __name__ == '__main__':
  fileNew = "D:\\FileDemo\\Python\\Test.py"
  renameFile(fileNew)

import os
from nt import chdir

def renameF(preName, newName):
  chdir(os.path.dirname(preName))
  os.rename(preName, newName)

if __name__ == '__main__':
  filePre = "D:\FileDemo\Python\PT.py"
  fileNew = "D:\FileDemo\Python\Test.txt"
  renameF(filePre, fileNew)