<s>
OPAL	B-Language
(	O
OPtimized	O
Applicative	O
Language	O
)	O
is	O
a	O
functional	B-Language
programming	I-Language
language	I-Language
first	O
developed	O
at	O
the	O
Technical	O
University	O
of	O
Berlin	O
.	O
</s>
<s>
This	O
is	O
an	O
example	O
OPAL	B-Language
program	O
,	O
which	O
calculates	O
the	O
GCD	O
recursively	O
.	O
</s>
