obitools4/autodoc/docmd/pkg/obiformats/empty_file.md

## `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).