Expression evaluation

binop.py

import operator


class Query(object):
    def __init__(self, name, val=None, left=None, right=None, op=None):
        self.name = name
        self.val = val
        self.left = left
        self.right = right
        self.op = op

    def __and__(self, other):
        name = '({} and {})'.format(self.name, other.name)
        return Query(name, left=self, right=other, op=operator.and_)

    def __or__(self, other):
        name = '({} or {})'.format(self.name, other.name)
        return Query(name, left=self, right=other, op=operator.or_)

    def __invert__(self):
        name = '~{}'.format(self.name)
        return Query(name, left=self, op=operator.not_)

    def eval(self):
        print('Eval({})'.format(self.name))
        if self.op is not None:
            left = self.left.eval()
            if self.right is None:
                print('{}({})'.format(self.op.__name__, left))
                return self.op(left)
            else:
                right = self.right.eval()
                print('{}({}, {})'.format(self.op.__name__, left, right))
                return self.op(left, right)
        else:
            print('val={}'.format(self.val))
            return self.val

how can I use it?