It was unclear to me what the `Amount.from_number()` "constructor" meant exactly. The currency that is created is given the number as the only input to construct the 20-byte representation, resulting in a type of "1". In the Currency class, the type "1" means an interest bearing currency. 

Before adding interest bearing currency parsing support the logic would return "1" as the string representation of the currency. Now the default iso_code (XRP) is used when constructing the currency and returned.