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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def getsuffix(subject):
 """ Returns the suffix of a filename. If the file has no suffix, returns None. Can return an empty string if the filenam ends with a period. """


  index = subject.rfind('.')
  if index > subject.replace('\\', '/').rfind('/'):
    return subject[index+1:]
  return None