Blit_consume copies between iobufs and advances src but does not advance dst.
val blit : src:([> Core__.Import.read ], seek) t ‑> dst:([> Core__.Import.write ], no_seek) t ‑> dst_pos:int ‑> len:int ‑> unitval blito : src:([> Core__.Import.read ], seek) t ‑> ?src_len:int ‑> dst:([> Core__.Import.write ], no_seek) t ‑> ?dst_pos:int ‑> unit ‑> unitval unsafe_blit : src:([> Core__.Import.read ], seek) t ‑> dst:([> Core__.Import.write ], no_seek) t ‑> dst_pos:int ‑> len:int ‑> unitval sub : ([> Core__.Import.read ], seek) t ‑> len:int ‑> (_, _) tval subo : ?len:int ‑> ([> Core__.Import.read ], seek) t ‑> (_, _) t