f
n__a
n__b
X
f
X
X
X
c
a
c
b
a
n__a
b
n__b
activate
n__a
a
activate
n__b
b
activate
X
X
2.2
activate
n__a
a
f
n__a
n__b
X
f
X
X
X
activate
n__b
b
c
a
c
b
true
c
b
false
c
a
false
activate
n__b
b
false
f
n__a
n__b
X
f
X
X
X
true
Failed!
NaTT
certifiable-1.6