Passing expressions to functions

In SQLAlchemy, it appears I'm supposed to pass an expression to filter() in certain cases. When I try to implement something like this myself, I end up with:

>>> def someFunc(value):
...     print(value)

>>> someFunc(5 == 5)
True

How do I get the values passed to == from inside the function?

I'm trying to achieve something like this

 >>> def magic(left, op, right):
 ...    print(left + " " + op + " " + right)

 >>> magic(5 == 5)
 5 == 5

What about if one of the parameters was an object?