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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 GetFsType(self):
 """Retrieves the file system type. Returns: pytsk3.TSK_FS_TYPE_ENUM: file system type. """

    if self._tsk_fs_type is None:
      self._tsk_fs_type = pytsk3.TSK_FS_TYPE_UNSUPP
      if (not self._tsk_file_system or
          not hasattr(self._tsk_file_system, 'info')):
        return self._tsk_fs_type

      self._tsk_fs_type = getattr(
          self._tsk_file_system.info, 'ftype', pytsk3.TSK_FS_TYPE_UNSUPP)

    return self._tsk_fs_type