The program itself is made of components that expose a low-level API, or otherwise you wouldn't use a low-level language. The API clients are other parts of you

The program itself is made of components that expose a low-level API, or otherwise you wouldn't use a low-level language. The API clients are other parts of your program. Programs written in low-level languages are much more tightly coupled than languages that support better abstraction (for the price of less control).