compile error when using override

[Ho Yeung Lee]

import ast 
from __future__ import division 
from sympy import * 
x, y, z, t = symbols('x y z t') 
k, m, n = symbols('k m n', integer=True) 
f, g, h = symbols('f g h', cls=Function) 
import inspect 

class A:
    @staticmethod
    def __additionFunction__(a1, a2):
        return a1*a2 #Put what you want instead of this
    def __multiplyFunction__(a1, a2):
        return a1*a2+a1 #Put what you want instead of this
    def __init__(self, value):
        self.value = value
    def __add__(self, other):
        return self.__class__.__additionFunction__(self.value, other.value)
    def __mul__(self, other):
        return self.__class__.__multiplyFunction__(self.value, other.value)

solve([A(x)*A(y) + A(-1), A(x) + A(-2)], x, y)


>>> solve([A(x)*A(y) + A(-1), A(x) + A(-2)], x, y)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 12, in __mul__
TypeError: unbound method __multiplyFunction__() must be called with A instance
as first argument (got Symbol instance instead)


import ast 
from __future__ import division 
from sympy import * 
x, y, z, t = symbols('x y z t') 
k, m, n = symbols('k m n', integer=True) 
f, g, h = symbols('f g h', cls=Function) 
import inspect 

 class AA:
    @staticmethod
    def __additionFunction__(a1, a2):
        return a1*a2 #Put what you want instead of this
    def __multiplyFunction__(a1, a2):
        return a1*a2+a1 #Put what you want instead of this
    def __init__(self, value):
        self.value = value
    def __add__(self, other):
        return self.__class__.__additionFunction__(self.value, other.value)
    def __mul__(self, other):
        return self.__class__.__multiplyFunction__(self.value, other.value)


ss = solve(AA)
ss([x*y + -1, x-2], x, y)

>>> ss([x*y + -1, x-2], x, y)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: solve instance has no __call__ method