|ext:gzip-bytes bytes &key start end level time file-name initial-length||[Function]|
Gzip compress the bytes vector from the start to end positions, returning a new compressed byte vector. The compression level may be between 0 and 9, and defaults to 6, with higher compression levels giving greater compression at the expense of longer compression times. An initial-length hint may be given which can help reduce consing growing the result vector. A file time in universal time format may be given which is stored in the gzip header and defaults to the current time. An optional file-name may also be given to be written into the header.