Function write_gff_output 

pub fn write_gff_output(
    gff_path: &Path,
    blocks: &[(u32, u64, u64)],
    output_path: &Option<PathBuf>,
    verbose: bool,
) -> Result<()>

Write selected byte ranges (“blocks”) of a GFF file to an output file or stdout.

Features:

• Uses memory-mapped I/O for efficiency.
• Merges adjacent or overlapping ranges before writing.
• Uses vectored I/O (write_vectored) to minimize syscalls.

Arguments

• gff_path: Path to the source GFF file.
• blocks: A list of (start, end) byte ranges to extract.
• output_path: Output file path. If None, writes to stdout.
• _allowed_types: Reserved for future filtering by feature type (currently unused).
• verbose: Whether to print diagnostic output.

Errors

Returns any I/O or mmap errors.