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

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Text this: The compound equation related to the Bessel-Helmholtz equation and the Bessel-Klein-Gordon equation