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 _    _    _    _     _____      ___      _  __  
| \  / || | || | ||  / ____||   / _ \\   | |/ // 
|  \/  || | || | || / //---`'  / //\ \\  | ' //  
| .  . || | \\_/ || \ \\___   |  ___  || | . \\  
|_|\/|_||  \____//   \_____|| |_||  |_|| |_|\_\\ 
`-`  `-`    `---`     `----`  `-`   `-`  `-` --`

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Text this: Head-on collisions of vortex rings upon round cylinders