You'll need to build a better version of your calculator using OOP and inheritance:

A calculator can be built with different operations. An Operation is an abstract class for which you'll define

subclasses.

Example:

```
calc1 = Calculator(operations={
'add': AddOperation,
'subtract': SubtractOperation})
calc2 = Calculator(operations={
'add': AddOperation})
```

The calculator has 1 generic method `calculate`

that will receive the arguments

and the operation to perform. For example:

```
calc1.calculate(2, 1, 5, 'add') # Should return 2 + 1 + 5 = 8
calc2.calculate(1, 5, 'add') # Should return 1 + 5 = 6
```

*IMPORTANT: The number of arguments should be variable*

The Calculator will check if it has that computation present and

invoke the operation. Operations are initialized with the arguments to compute:

```
op = AddOperation(2, 1, 5)
```

Once you have an operation object created you should be able to invoke the `operate`

method PRESENT IN EVERY OPERATION.

```
op.operate() # Should return 8
```

*Important notes:*

* The only method that you must implement for every operation (descendant from Operation) is the operate method.
* If the operation is not supported by the calculator (for example invoking

`multiply`

on calc1) the calculator should raise a custom exception (built by you) named `OperationInvalidException`

.### Test Cases

tests

`[]`