The unary - (minus) operator yields the negation of its
numeric argument.
The unary + (plus) operator yields its numeric argument
unchanged.
The unary ~ (invert) operator yields the bit-wise inversion
of its plain or long integer argument. The bit-wise inversion of
x is defined as -(x+1). It only applies to integral
numbers.
In all three cases, if the argument does not have the proper type,
a TypeError exception is raised.