## `ReadEmptyFile` Function — Semantic Description - **Package**: `obiformats`, part of the OBITools4 ecosystem for biological sequence handling. - **Purpose**: Creates and returns an *empty*, closed iterator over biosequences (`IBioSequence`). - **Signature**: `func ReadEmptyFile(options ...WithOption) (obiiter.IBioSequence, error)` - **Input**: Accepts variadic `WithOption` configuration functions (currently unused in this minimal implementation). - **Behavior**: - Instantiates a new `IBioSequence` iterator via `obiiter.MakeIBioSequence()`. - Immediately closes the stream using `.Close()` — indicating no data will be yielded. - **Output**: - Returns a *terminal* iterator (no elements), suitable as a safe default or fallback. - Error return is always `nil`, since no I/O occurs and the operation is deterministic. ### Semantic Role & Use Cases - **Default/Placeholder**: Useful in conditional logic where a valid (but empty) sequence iterator is required when no input file exists or parsing fails. - **Consistency**: Ensures callers always receive a well-formed iterator, avoiding `nil` checks. - **Resource Safety**: The closed state prevents accidental iteration or memory leaks. ### Design Notes - Reflects a *pure-functional* and *fail-safe* pattern: no side effects, deterministic behavior. - Aligns with iterator-based I/O design principles in OBITools4 (lazy, composable streams).