Function merge_block_delimiters 

pub fn merge_block_delimiters(sequences: &mut [ExternalSequence]) -> usize

Remove every block delimiter from sequences, handing its literals to the sequence after it, and return how many sequences remain at the front (C ZSTD_mergeBlockDelimiters). A final delimiter’s literals become the parse’s trailing literals, which no sequence carries.

use structured_zstd::encoding::sequences::{merge_block_delimiters, ExternalSequence};
let mut parse = [
    ExternalSequence { offset: 4, lit_len: 2, match_len: 5, rep: 0 },
    ExternalSequence { offset: 0, lit_len: 3, match_len: 0, rep: 0 },
    ExternalSequence { offset: 9, lit_len: 1, match_len: 4, rep: 0 },
];
assert_eq!(merge_block_delimiters(&mut parse), 2);
assert_eq!(parse[1].lit_len, 4);