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            _____    _    _     ______    _  __  
    ___    |  ___|| | \  / ||  /_   _//  | |/ // 
   /   ||  | ||__   |  \/  ||   -| ||-   | ' //  
  | [] ||  | ||__   | .  . ||   _| ||_   | . \\  
   \__ ||  |_____|| |_|\/|_||  /_____//  |_|\_\\ 
    -|_||  `-----`  `-`  `-`   `-----`   `-` --` 
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Text this: Studies of delta operator and its application to a tank level control process