<s>
Flow	B-Application
chart	I-Application
language	I-Application
(	O
FCL	O
)	O
is	O
a	O
simple	O
imperative	B-Application
programming	I-Application
language	I-Application
designed	O
for	O
the	O
purposes	O
of	O
explaining	O
fundamental	O
concepts	O
of	O
program	O
analysis	O
and	O
specialization	O
,	O
in	O
particular	O
,	O
partial	O
evaluation	O
.	O
</s>
<s>
FCL	O
is	O
an	O
imperative	B-Application
programming	I-Application
language	I-Application
close	O
to	O
the	O
way	O
a	O
Von	B-Architecture
Neumann	I-Architecture
computer	I-Architecture
executes	O
a	O
program	O
.	O
</s>
<s>
We	O
write	O
a	O
program	O
that	O
computes	O
the	O
nth	O
Fibonacci	B-Algorithm
number	I-Algorithm
,	O
for	O
n>2	O
:	O
</s>
<s>
Where	O
the	O
loop	O
invariant	O
of	O
is	O
that	O
x1	O
is	O
the	O
(	O
i+	O
2-1	O
)	O
th	O
and	O
x2	O
is	O
the	O
(	O
i+2	O
)	O
th	O
Fibonacci	B-Algorithm
number	I-Algorithm
,	O
where	O
i	O
is	O
the	O
number	O
of	O
times	O
has	O
been	O
jumped	O
to	O
.	O
</s>
