Function:

• Initiated with a currency type (USD, EUR, JPY, etc) and value (int/float) Methods:
• add : allows user to combine the two values of like-currency_type values
• sub : allows user to subtract second value from first value of like-currency_type values
• mul : allows user to multiply two like-currency_type values

Function:

• Provide an error code for an attempt to compute two different-currency_type values

#CurrencyConverter class Function:

• Initiated with a dictionary of currency_types (key) and respective rates (value) Methods:
• convert(): Takes a Currency class object and target, new currency_type and original to target

Function:

• Provide an error code for an attempt to convert with an unknown currency_type