def evaluate(expression):
    """
    Calculate result of expression

    expression String: The expression
    type Type (optional): Number type [int, float]
    """
    op_stack  = deque() # operator stack
    out_stack = deque() # output stack (values)
    tokens = parse(expression) # calls the function only once!
    for token in tokens:
        if numeric_value.match(token):
            out_stack.append(float(token))
        elif token == '(':
            op_stack.append(token)
        elif token == ')':
            while len(op_stack) > 0 and op_stack[-1] != '(':
                apply_operation(op_stack, out_stack)
            op_stack.pop() # Remove remaining '('
        else: # is_operator(token)
            while len(op_stack) > 0 and is_operator(op_stack[-1]) and higher_priority(op_stack[-1], token):
                apply_operation(op_stack, out_stack)
            op_stack.append(token)

    while len(op_stack) > 0:
        apply_operation(op_stack, out_stack)

    return out_stack[-1]
Calculate result of expression

    expression String: The expression
    type Type (optional): Number type [int, float]