https://www.programiz.com/python-programming/methods/built-in/eval
def basic_op(operator, value1, value2):
if operator=='+':
return value1+value2
if operator=='-':
return value1-value2
if operator=='/':
return value1/value2
if operator=='*':
return value1*value2
can be written as:
def basic_op(operator, value1, value2):
return eval("{}{}{}".format(value1, operator, value2))