abbrev
base64
benchmark
bigdecimal
bigdecimal-math
cgi
coverage
csv
date
dbm
delegate
did_you_mean
digest
erb
etc
fileutils
find
forwardable
io-console
ipaddr
json
kconv
logger
minitest
monitor
mutex_m
net-http
net-protocol
net-smtp
nkf
objspace
observable
open-uri
open3
openssl
optparse
pathname
pp
prettyprint
pstore
psych
pty
rdoc
resolv
ripper
securerandom
shellwords
singleton
socket
stringio
strscan
tempfile
time
timeout
tmpdir
tsort
uri
yaml
zlib