~ -- a unary or binary operator, often used for bitwise negation

This operator may be used as a binary operator in an expression like x~y. The user may install binary methods for handling such expressions with code such as

         X ~ Y := (x,y) -> ...

where X is the class of x and Y is the class of y.

This operator may be used as a prefix unary operator in an expression like ~y. The user may install a method for handling such expressions with code such as

           ~ Y := (y) -> ...

where Y is the class of y.