What's interesting in that case is I would argue the interface code is MORE important than the implementing code. You can hire any SWE to re-implement the entir

What's interesting in that case is I would argue the interface code is MORE important than the implementing code. You can hire any SWE to re-implement the entire API and it being pretty straightforward. The interface code was what actually mattered with developers and took creative expression, design, sequence, organization to put together and feedback and iteration over the years. Google knew this too, taking the interface code was WAY more important for them than if they had done the reverse.