docs: def unpackfile(filename, destdir):
      """Unpack a mar or exe into destdir"""
      if filename.endswith(".mar"):
          return unpackmar(filename, destdir)
      elif filename.endswith(".exe"):
          return unpackexe(filename, destdir)
      elif filename.endswith(".tar") or filename.endswith(".tar.gz") \
              or filename.endswith(".tgz"):
          return unpacktar(filename, destdir)
      else:
          raise ValueError("Unknown file type: %s" % filename)