I am learning Python for the past few days and I have written this piece of code to evaluate a postfix expression.

```
postfix_expression = "34*34*+"

stack = []

for char in postfix_expression :
    try :
        char = int(char);
        stack.append(char);
    except ValueError:
        if char == '+' :
            stack.append(stack.pop() + stack.pop())
        elif char == '-' :
            stack.append(stack.pop() - stack.pop())
        elif char == '*' :
            stack.append(stack.pop() * stack.pop())
        elif char == '/' :
            stack.append(stack.pop() / stack.pop())

print stack.pop()

```

Is there a way I can avoid that huge if else block? As in, is there module that takes a mathematical operator in the string form and invokes the corresponding mathematical operator or some python idiom that makes this simple?