Utility takes records from stdin, where each record has 64-bit
big-endian length prefix.
-unzstd decompressed Zstandard frames stream from stdin to stdout. If
+unzstd decompresses Zstandard frames stream from stdin to stdout. If
stream starts with the dictionary (either compressed, or uncompressed)
it is loaded first. If 3rd file descriptor is opened, then each frame's
offset (its size) with decompressed data size is printed in