Select items from a yspec object via flags
Examples
spec <- ys_help$spec()
ys_select_fl(spec, nm, times)
#> name info unit short source
#> ID --- . subject identifier ysdb_internal
#> TIME --- hour TIME look
#> CMT --- . compartment number ysdb_internal
#> AMT --- mg dose amount ysdb_internal
#> MDV -d- . MDV ysdb_internal
#> TAD --- hours time after dose .
