Use worst case for both possible values.

        >>> import gast as ast
        >>> from pythran import passmanager, backend
        >>> node = ast.parse('''
        ... def foo():
        ...     a = 2 or 3
        ...     b = 4 or 5
        ...     c = a if a else b''')
        >>> pm = passmanager.PassManager("test")
        >>> res = pm.gather(RangeValues, node)
        >>> res['c']
        Interval(low=2, high=5)

def visit_IfExp(self, node):
        """ Use worst case for both possible values.

        >>> import gast as ast
        >>> from pythran import passmanager, backend
        >>> node = ast.parse('''
        ... def foo():
        ...     a = 2 or 3
        ...     b = 4 or 5
        ...     c = a if a else b''')
        >>> pm = passmanager.PassManager("test")
        >>> res = pm.gather(RangeValues, node)
        >>> res['c']
        Interval(low=2, high=5)
        """
        self.visit(node.test)
        body_res = self.visit(node.body)
        orelse_res = self.visit(node.orelse)
        return self.add(node, orelse_res.union(body_res))