Вычисление выражения без использования функции eval

def evaluate(expression):
    tokens = tokenize(expression)
    numbers = []
    operators = []
    for token in tokens:
        if token.isdigit():
            numbers.append(int(token))
        elif token == "(":
            operators.append(token)
        elif token == ")":
            while operators[-1] != "(":
                operator = operators.pop()
                num2 = numbers.pop()
                num1 = numbers.pop()
                result = perform_operation(operator, num1, num2)
                numbers.append(result)
            operators.pop()
        else:
            while operators and get_priority(operators[-1]) >= get_priority(token):
                operator = operators.pop()
                num2 = numbers.pop()
                num1 = numbers.pop()
                result = perform_operation(operator, num1, num2)
                numbers.append(result)
            operators.append(token)
    while operators:
        operator = operators.pop()
        num2 = numbers.pop()
        num1 = numbers.pop()
        result = perform_operation(operator, num1, num2)
        numbers.append(result)
    return numbers[0]
 
def tokenize(expression):
    tokens = []
    current_token = ""
    for char in expression:
        if char.isdigit():
            current_token += char
        else:
            if current_token:
                tokens.append(current_token)
                current_token = ""
            tokens.append(char)
    if current_token:
        tokens.append(current_token)
    return tokens
 
def get_priority(operator):
    if operator in ["+", "-"]:
        return 1
    elif operator in ["*", "/"]:
        return 2
    else:
        return 0
 
def perform_operation(operator, num1, num2):
    if operator == "+":
        return num1 + num2
    elif operator == "-":
        return num1 - num2
    elif operator == "*":
        return num1 * num2
    elif operator == "/":
        if num2