sel
s
X
cons
Y
sel
X
Z
sel1
s
X
cons
Y
sel1
X
Z
first1
s
X
cons
Y
cons1
quote
first1
X
Z
quote
sel1
X
Z
quote1
first1
X
Z
sel
0
cons
X
X
first
0
Z
nil
first
s
X
cons
Y
cons
Y
from
X
cons
X
sel1
0
cons
X
quote
first1
0
Z
nil1
quote
01
quote1
cons1
quote
quote1
quote1
nil1
quote
s1
quote
unquote
01
0
unquote
s1
X
s
unquote
X
unquote1
nil1
nil
unquote1
cons1
X
Z
fcons
unquote
X
unquote1
Z
fcons
X
Z
cons
X
2.2
NaTT
certifiable-1.6