Function semq_encoding_concat 

pub unsafe extern "C" fn semq_encoding_concat(
    parts: *const *const semq_encoding_t,
    k: u32,
    out: *mut *mut semq_encoding_t,
    err: *mut semq_error_t,
) -> semq_status_t

Merge k Encodings with the same config, id kind and manifest and pairwise-disjoint ids.