docs: def _pprint_line(line, annotations=None, annotation_file=None,
                   block_length=10, blocks_per_line=6):
      """
      Pretty-print one line.
      """
      annotations = annotations or []
  
      if annotation_file:
          # We just use the first chromosome defined in the BED file.
          _, chrom_iter = next(_bed_iter(annotation_file))
          annotations.append(list(chrom_iter))
  
      print(pprint_sequence(line, annotations=annotations,
                            block_length=block_length,
                            blocks_per_line=blocks_per_line, format=AnsiFormat))