Modified the portfolio class to add the possibility of adding two instances together.
For this I first added the validation of the second instance being of the same type (portfolio), if not, raise an error.
Then take the tokens values and add them together to return a new portfolio instance containing these new values.
Issue:
Resolves #113
Summary:
Modified the portfolio class to add the possibility of adding two instances together. For this I first added the validation of the second instance being of the same type (portfolio), if not, raise an error. Then take the tokens values and add them together to return a new portfolio instance containing these new values.