"15 // 0"  ➞ -1

arithmetic_operation("12 + 12") ➞ 24 // 12 + 12 = 24

arithmetic_operation("12 - 12") ➞ 24 // 12 - 12 = 0

arithmetic_operation("12 * 12") ➞ 144 // 12 * 12 = 144

arithmetic_operation("12 // 0") ➞ -1 // 12 / 0 = -1

>>separate the number and operator in the string by space
  call split() method
>>perfrom action based whether it is a number or valid operator
  import operator module
  build a dictionary with key=the operator string, value = the equivent function
  check the second separated part, which must be operator, to call the equivent function from the dictionary
  pass the first and thrid element as argument to the function
>>return the result

import operator  


def arithmetic_operation(math_sting: str):  
    # split the string  
    splited_list = math_sting.split()  
    first_num = int(splited_list[0])  
    second_num = int(splited_list[-1])  
    operation_to_call = splited_list[1]  
    # In case of division, whenever the second number equals "0" return`-1`.  
    if operation_to_call == "//" and second_num == 0:  
        return -1  
    # setup dictionary to call the maths operation  
    math_dictionary = {"+": operator.add(first_num, second_num),  
                       "-": operator.sub(first_num, second_num),  
                       "*": operator.mul(first_num, second_num),  
                       "//": operator.floordiv(first_num, second_num)}  
    # find the equivalent operation from the dictionary and store the result  
    result = math_dictionary[operation_to_call]  
    return result

def arithmetic_operation(equation):  
    '''  
    Returns the result of evaluating the string equation    '''   
    from operator import add, sub, floordiv, mul  

    operator_dict = {'+': add, '-': sub, '*': mul, '//': floordiv}  
    # split the equation into three part  
    first_num, operation, second_num = equation.split()  

    try:  
        # call the operation from the dictionary and perform the calculation  
        return operator_dict[operation](int(first_num), int(second_num))  
    # In case of division, whenever the second number equals "0" return`-1`.  
    except ZeroDivisionError:  
        return -1

def arithmetic_operation(equation):  
    first_num, operation, second_num = equation.split()  
    if operation == '+':  
        return int(first_num) + int(second_num)  
    if operation == '-':  
        return int(first_num) - int(second_num)  
    if operation == '*':  
        return int(first_num) * int(second_num)  
    if operation == '//' and second_num == '0':  
        return -1  
    return int(first_num) // int(second_num)