Get the underlying segment from a shared vector
Examples
# \donttest{
x <- as_shared(1:100)
shared_segment(x)
#> <shard_segment>
#> Size: 400 bytes
#> Backing: mmap
#> Path: /tmp/shard_7143_1774903678_1774903677
#> Read-only: TRUE
#> Owns segment: TRUE
# }