This class lets you overide operations, __power__, __mul__,
__div__, __mod__, __add__, __sub__, __getitem__, __lshift__,
__rshift__, __and__, __xor__, __or__,__pos__, __neg__, __not__,
__repr__, __invert__, and __getattr__.
For example, __mult__ might be overridden to prevent expressions like:
'I like spam' * 100000000
or to disallow or limit attribute access.