customizing and/or/not

[Simon Burton]

Just reading about the new Sets... and this came up.
Why can't we customize the and/or/not operators?
I see this as making one's own boolean type.
Is it possible?

class myBool:
  def __land__(self,other):
  def __lor__(self,other):
  def __lnot__(self,other):

or even:
  def __in__(self,item):
  def __nin__(self,item):

I guess i'm wondering why we cant use and/or with lists/sets etc.
It's perhaps too funky.

Simon Burton.