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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 descfile(family_directory):
 """Get the path of the DESCRIPTION file of a given font project."""

  if family_directory:
    descfilepath = os.path.join(family_directory, "DESCRIPTION.en_us.html")
    if os.path.exists(descfilepath):
      return descfilepath