u
s
s/
s//
s/foo
s/foo\/foo
s/foo/bar
s/foo/bar\/bar
s/foo/bar/@
s/foo/bar/@g
s/foo/bar/g@
s/foo/bar//
s/foo/bar/w
y
y/
y//
y/a
y/a/b
y/a/b/g
