a $=$ 'cat'

b $=$ 'mouse'

c $=[$a$,$ b$]$

d $=$ c

d$[0]=$ 'bird'

if $($b is d$[1])$:

print$(\text{'}$f$\text{'})$

if $($c is d$)$:

print$(\text{'}$g$\text{'})$

if $($a is d$[0])$:

print$(\text{'}$h$\text{'})$